She goes to restaurants or playgrounds with her female friends

The confirmed basic principle with regard to the Muslim
woman is that she should stay in her house and keep away from places and
situations that involve mixing with non-mahram men; she should also strive
to cover herself completely and protect herself from immodest behaviour
with others. All of that and more is part of the etiquette of hijab,
clothing, modesty and chastity, seeking to purify hearts and keep them
free of immorality and corruption. Allah, may He be exalted, says:

“And stay in your houses, and do not display yourselves
like that of the times of ignorance, And perform
As‑Salaah(Iqâmat‑as-Salaah), and give Zakaat and obey Allaah and His
Messenger. Allaah wishes only to remove Ar‑Rijs (evil deeds and sins) from
you, O members of the family (of the Prophet
صلى الله عليه وسلم), and to purify you with a thorough purification”

[al-Ahzaab 33:33]. 

Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him)
said: 

When the Muhaajiroon came to Madeenah, the single men used to
stay in a house that was well known and was separate from the houses of
those who had families, so a single should not stay among those who have
families. All of that is because if one of the two types mixes with the
other, it will lead to fitnah (temptation). If mixing men with women is
mixing fire with wood. Al-Istiqaamah (1/361). 

Al-Imam Ibn al-Qayyim (may Allah have mercy on him) said: 

There is no doubt that making it possible for women to mix
with men is the sources of all corruption and evil, and it is one of the
greatest causes of punishments coming upon the entire community. It is also
one of the causes of corruption in public and private affairs. Mixing of men
with women is the cause of a great deal of immoral conduct and zina. 

Al-Turuq al-Hukmiyyah, 407. 

Once this is clear, it is not permissible for women to go to
places where they mix with men, whether it is a playground, a club,
restaurant or a house, even if that is with the permission of the husband.
What the husband should do is prevent her from going to places in which it
is possible for her to mix with non-mahram men. 

But if these places are only for women, or there are hours
which are only for women, in which no men take part, and men cannot look at
the women or contact them, and fitnah is not possible, then it is
permissible for a woman to go to these places with other women, if her
husband gives her permission for that. But we think that this assumption is
not realistic; rather such places are not available in the greater part of
the Muslim world so how about in the West? 

And Allah knows best.