Should she cut off ties with her family who are trying to lead her astray and are opposed to her becoming righteous?

Firstly: 

Verily to Allaah we belong and unto Him is our return. By
Allaah, it fills the heart with sorrow to hear that there is such severe
suffering and pain in Muslim families for the one who wants to adhere to his
religion and straight path. We have often heard of Muslim men and women who
suffer because of their Christian or idol-worshipping families, but for a
Muslim woman to suffer because of her family who claim to be Muslims and to
flee from her so-called Muslim family for the sake of her religious
commitment is something that is very sad. 

We ask Allaah to make you and your husband steadfast in
adhering to Islam and true guidance, and to make you strong in adhering to
the truth, and to make you righteous and bless you with righteous
offspring. 

Muslim narrated in his Saheeh (145) that Abu Hurayrah
(may Allaah be pleased with him) said: The Messenger of Allaah (peace
and blessings of Allaah be upon him) said: “Islam began as something strange
and will revert to being something strange, so glad tidings to the
strangers.” If the people regard you as strange because of your religious
commitment, then glad tidings to you. If the Muslim sees that he is a
stranger because of his Islam, even among his family, then this is glad
tidings for him that the Messenger (peace and blessings of Allaah be
upon him) conveyed to him: “Glad tidings to the strangers.” 

There can be no doubt that reviling the Lord and Islam, as
done by your mother and other family members, is major kufr that puts a
person beyond the pale of Islam and dooms them to Hell for eternity, if the
one who did that dies without coming back to Islam. 

Hence your duty towards those among your family who have
fallen into such sins is to call them to refrain from this kufr and tell
them that they must come back to Islam, and they should understand their
situation and the Islamic ruling on their case, which is that they are
apostates whose good deeds have been cancelled out. 

You should realize that the fact that your mother has fallen
into kufr does not mean that you should sever your relationship with her,
rather you should be more concerned about it lest she die in this state. 

You have to honour her and treat her kindly even if she is a
kaafir and, moreover, even if she calls you to kufr and strives hard to do
that, as our Lord, may He be glorified and exalted, says (interpretation of
the meaning): 

“And We have enjoined on man to be good and dutiful to his
parents; but if they strive to make you join with Me (in worship) anything
(as a partner) of which you have no knowledge, then obey them not”

[al-‘Ankaboot 29:8] 

“But if they (both) strive with you to make you join in
worship with Me others that of which you have no knowledge, then obey them
not; but behave with them in the world kindly”

[Luqmaan 31:15]. 

It was narrated that Asma’ bint Abi Bakr (may Allaah be
pleased with her) said: My mother came to me when she was a mushrik. I
consulted the Messenger of Allaah (S) and said: O Messenger of Allaah (S),
my mother has come to me and she is expecting (something), should I uphold
the ties of kinship with my mother? He said: “Yes, uphold the ties of
kinship with your mother.” Narrated by al-Bukhaari (2620) and Muslim
(1003). 

But this honouring and showing kindness does not mean that
you have to mix with them in their homes and get involved in their lives
where they commit sins and revile Allaah and His Messenger and His Religion,
unless your presence will put a stop to this kufr and these sins. But if
they will are ongoing and there is the possibility that you may be affected
by what you hear, then it is haraam for you to stay in that gathering with
them. If they repeat that every time you visit, then there is nothing wrong
with you not visiting them, and that is not being disobedient to them,
rather it is a shar’i obligation. Allaah says (interpretation of the
meaning): 

“And it has already been revealed to you in the Book (this
Qur’aan) that when you hear the Verses of Allaah being denied and mocked at,
then sit not with them, until they engage in a talk other than that; (but if
you stayed with them) certainly in that case you would be like them”

[al-Nisa’ 4:140]

Do not pay any attention to your family’s forsaking you
because of your and your husband’s commitment to the rulings of sharee’ah on
clothing and other matters, because this is one of the tricks of the
shaytaan. 

The scholars of the Standing Committee said, concerning a
similar issue: 

Obeying one’s parents is required in that which is good and
proper, but if they tell you to commit sin, then there is no obedience to
them, because it is proven that the Prophet (peace and blessings of
Allaah be upon him) said: “Obedience is only in that which is good and
proper.” So adhere to your hijab and try to convince them and explain the
rulings to them, and do not pay any attention to their threats. Seek the
help of Allaah, may He be glorified, in that, then seek the help of good
people among your relatives who can advise them, in the hope that Allaah may
benefit them thereby. End quote. 

Fataawa al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah
wa’l-Ifta’ (1/541) 

It is strange that your mother has fallen into kufr, evil and
sin, then we see her showing concern about your disobedience to her, and
accuses you thereof. This contradiction is indicative of ignorance of
sharee’ah and a lack of concern about its rulings. 

To sum up: The Muslim woman is obliged to treat her family
and parents well, and to do her utmost to advise them with goodness, wisdom
and beautiful preaching. She should regard the period when she cuts off ties
with them – for the sake of her religious commitment – as a temporary
remedy, and if she feels that her family have made some change for the
better, she should hasten to resume ties with them and guide them towards
that which is good. 

Do not forget to pray for your mother and your family, asking
Allaah to guide them and bring them back to their true religion before it is
too late. 

And Allaah knows best.