Joining Maghrib and ‘Isha’ because of the curfew

Firstly: 

Yes, in your situation it is permissible to combine Maghrib
and ‘Isha’ prayers. It is narrated in the Sunnah that the Prophet
(peace and blessings of Allaah be upon him) used to join Maghrib and ‘Isha’
prayers because of rain. Muslim (705) narrated from Sa’eed ibn Jubayr that
Ibn ‘Abbaas (may Allaah be pleased with him) said: The Messenger of Allaah
(peace and blessings of Allaah be upon him) joined Zuhr and ‘Asr, and
Maghrib and ‘Isha’ in Madeenah at times other than times of fear or rain. I
said to Ibn ‘Abbaas: Why did he do that? He said: So that his ummah would
not be faced with hardship. 

The fact that Ibn ‘Abbaas (may Allaah be pleased with him)
stated that it was not because of fear or rain indicates that these are
two of the reasons for joining prayers. 

Shaykh al-Islam [Ibn Taymiyah] said:  

It is permissible to combine the two evening prayers because
of rain, strong cold winds or muddy conditions and the like, and this is the
more correct scholarly view. This is the view of the madhhabs of Ahmad,
Maalik and others.  

And he said: It is permissible to combine prayers in the case
of severely muddy conditions or severe cold wind on a dark night, etc, even
if rain is not actually falling, according to the more sound of the two
scholarly opinions. That is better than praying in one’s home, because not
joining the prayers in the mosque and praying at home instead is an
innovation that is contrary to the Sunnah. The Sunnah is to offer the five
daily prayers in the mosque in congregation, and that is better than praying
at home, according to the consensus of the Muslims. Joining the prayers in
the mosque is better than praying them separately at home according to the
consensus of those imams who regard joining the prayers as permissible, such
as Maalik and al-Shaafa’i. End quote. 

Majmoo’ al-Fataawa, 24/30 

In your situation, the
reason for joining the prayers is undoubtedly more pressing than rain. 

Secondly: 

Joining the prayers in
this case applies to those who are required to pray in congregation. As for
sick people who pray at home, or women who pray at home, it is not
permissible for them to join their prayers. 

Shaykh Ibn ‘Uthaymeen said in al-Sharh al-Mumti’,
4/288 

But if a person prays at home because of sickness and does
not attend the mosque, then it is not permissible for him to join the
prayers, because that will not benefit him. Similarly a woman is not
permitted to join her prayers because of rain, because she will not benefit
from doing so, as she is not one of those who are required to pray in
congregation. End quote. 

See also the answer to question no.
31172. 

Thirdly: 

With regard to his giving the adhaan for ‘Isha’ at the time
for ‘Isha’, there is nothing wrong with that, so that those who are praying
at home, such as women and the sick, will know that the time for ‘Isha’
prayer has begun. 

Fourthly: 

Your describing the imam of your mosque as not having much
knowledge of fiqh because he joins Maghrib and ‘Isha’ would seem to be a
mistake, as you now know that this action of his is correct, based on the
evidence noted above. 

You should have been easygoing and not hastened to denounce
something until you knew whether it was wrong. You should not attribute
ignorance to your brother without proof. 

Fifthly: 

The fear prayer may be done in several ways, according to the
situation and whether the enemy is in the direction of the qiblah or not. We
have explained that in the answer to question no
36896 . 

And Allaah knows best.