In the Name of Allah, the All-Merciful, the Mercy-Giving

 

 All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad.

 

If a woman is divorced, then she becomes a stranger like any other woman who is not related to him in marriage or blood relations. If a woman who is not a mahram to your father can visit his home for a legitimate reason, your mother is also allowed to do the same. The only condition is they can not be alone or isolated with each other.

 

Any other strictures regarding this issue are customs, and not based on strict religious teachings.

 

So, your mother is allowed to visit her children at home.

 

Almighty Allah knows best.