My grandmother fractured her femure during an accident, what can be done to aid in the healing?

Therapy/nutrition. It is pertinent that your grandmother follow her physical therapists recommendations to the t. Also, it is vital that her nutritional status is evaluated, making sure she has enough protein in her diet to ensure appropriate healing. If not already performed, her bones should be evaluated for osteoporosis, and treatment should be initiated if possible, to avoid future fractures.
See orthopedist. Follow advice and instructions work on fall prevention.