Is it permissible for a Muslim, who is the heir of a disbeliever, to take money from the inheritance and give it to his disbelieving mother?

A Muslim does not inherit from a disbeliever. Consequently, it is impermissible for a Muslim to take money from the estate of their disbelieving relative, nor to spend it on their mother or anyone else, whether they be disbelievers or Muslims; because he does not own the money, nor is he authorized to dispose of it.