You did not specify in your post but I will assume your mother has a fracture of the 5th metatarsal. There are 2 types generally seen at the base or tuberosity of the 5th metatarsal. An avulsion fracture, where the peroneus brevis tendon yanks off a piece of bone and a Jones fracture a bit further up the bone. This one is very difficult to heal. Sometimes surgery is indicated, sometimes a bone stimulator is helpful.
Immobilization is what is indicated. No fracture on any part of the body will heal quickly if it continuously moved around. The broken pieces need to be close together so they can reunite.