What is the ruling on living with a disbelieving mother and moving one's wife to live with her in the same house?

There is no objection to a son living with his disbelieving mother, and it is not permissible for him to disobey her or mistreat her in word or deed. Rather, it is obligatory to treat her kindly; perhaps that will be a cause for her guidance, provided that he does not obey her in sin or compromise with her in her disbelief, based on the Almighty's saying: "And We have enjoined upon man goodness to his parents. But if they endeavor to make you associate with Me that of which you have no knowledge, then do not obey them. To Me is your return, and I will inform you about what you used to do." (Al-Ankabut: 8), and His saying: "But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them. But accompany them in [this] world with kindness" (Luqman: 15).