Backpacks are awkward to handle with crutches. I would make a small bag to hank around her neck that she can get to easily. They can be made of a beautiful fabric, or jeans material with a pocket on the side, or leather from an old leather coat. I bought a small bag that was made of denim and it is very handy to get to and it holds just the essentials.It was made by residents of a nursing home as a fund raiser for their craft department.