Is it permissible to sever ties of kinship with the mother's and father's families who exploit the mother's kindness and cause her exhaustion and humiliation, even though the mother justifies her help to them by saying they are her siblings and that good deeds are not lost with Allah?

Kinship ties are obligatory to uphold and forbidden to sever. The misbehavior of some relatives does not permit cutting them off entirely. Rather, it is obligatory to maintain ties with them to the extent and in a manner that does not harm the one who upholds the ties. She must maintain ties with her relatives in a good way, and if they mistreat her mother, she should advise them or find someone to advise them. She should also advise her mother to be gentle with herself, while observing the proper etiquette of advising one's mother.