Is it religiously obligatory for me to maintain kinship ties with this woman (the husband's mother), socialize with her, and endure her, and whatever the husband demands in that regard, given what the wife suffers from her actions, as she seeks to separate the spouses and constantly interferes in their lives?

Merely being the mother of the wife does not make her among the kin (Arham) whose ties must be maintained, unless she is a close relative like a paternal aunt (ammah) or a maternal aunt (khalah). It is permissible to refrain from visiting her if her harm is feared, and the husband does not have the right to compel you to visit her. It is permissible to prevent children from visiting their grandmother if mischief (mafsadah) is feared for them. This woman must be advised gently, reminded of Allah, and of the evil consequences of her actions. Regarding the treatment of the sick son, the husband does not have the right to prevent you from doing so, and you may take from his money without his knowledge to meet the need if he refuses to pay. You must advise your husband gently and kindly, remind him of your right, and warn him against being deceived by his mother's words, and that he should act according to the legal principle: "O you who have believed, if there comes to you a disobedient one with information, investigate" [Quran 49:6]. Be keen on understanding to maintain family stability.