All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If this woman left her husband's house without his permission, she is a disobedient wife; one must advise her to fear Allaah and return to her husband's house. If she does not accept, she loses her right for expenses and accommodation.
However, the disobedience of a wife does not make her lose her right in the fostering of her child if she is eligible for fostering him. However, she is not permitted to prevent her husband from seeing his child as he has a right to do so.
Therefore, we advise both spouses to endeavour to reconcile and seek the help of pious and righteous people in this regard, as reconciliation is good and dispute is evil. If the efforts of reconciliation are of no avail, then the matter should be taken to an Islamic court.
For more benefit, please refer to Fatwa 84575.
Allaah Knows best.