Shouldn't do any harm. Do you have Arnica tablets? That could be better.
For muscular strains etc, Rhus Tox is good, and for ligaments, Ruta Grav, but general over-exertion, arnica's good.
Do you give her any supplements normally? Maight be worth thinking about Glucosamine or Green Lipped Mussel or something once her leg's fixed.
Sending her Reiki, how about a hot water bottle? Or a blanket. Let her take it easy for a day or two (if she wants to )