What is the ruling of Islamic law regarding a mother's humiliating treatment of her disabled son and husband, because the father registered the house in the son's name, knowing that the mother is in need of care?

If the registration of the house in your name was a gift, then you have a right to it, subject to its conditions. If it was a will (وصية) made after death, it is invalid for an heir. The mother is not permitted to insult the father, and he has guardianship over her (القوامة). Her assumption that the will would deprive her of inheritance is incorrect, because it is an invalid will and does not affect her right. The care of both parents is obligatory upon all children. If they have no son other than you, then their care becomes obligatory upon you. You have the right to live in a separate house without neglecting their care, though it is preferable not to do so unless there is a need. Threatening parents with leaving contradicts honoring them and could lead to disobedience (عقوق).