What is the ruling regarding a mother cutting ties with her sisters and brother, after their repeated harm to her and her family, their involvement in sorcery and charlatanry, and their defiance of the doctor's instructions in caring for their disabled parents? And is she sinful if she buys cigarettes for her father at his request?

It is not permissible to go to sorcerers, soothsayers, or diviners, nor to believe them. Whoever does so has disbelieved in what was revealed to Muhammad, or their prayers will not be accepted for forty days. As for boycotting relatives due to their actions, it is forbidden. A Muslim should respond to their ill-treatment with kindness and patience, for there is a great reward in that. It is not permissible for your mother to buy cigarettes for your grandfather, because smoking is an act of disobedience, and "there is no obedience to a creature in disobedience to the Creator."