Training takes time, effort, bonding, and rewards. Dogs don’t just ~do things~ because you tell them to. So if your mom doesn’t spend time with your dog, and only tells him what to do, there’s is a big chance he isn’t going to listen because it isn’t beneficial to him. He doesn’t have the desire to please your mom, nor does he get anything in return.
Dogs do not have a hierarchy system, and dogs are not people, so he doesn’t know or care that she is the head of your household. Dogs also have a tough time listening when they are anxious or under stimulated, so if your dog likes to pace around at night, yelling at him to sit down isn’t going to fix anything, giving him more exercise or play time during the day will.