I would put a small sleeve to accomate say a 1"pole, hand stitch it on and then mount the pole hangers on the wall and hang that way. If you have any of the backing fabric left over then it would hardly be noticeable. This will keep the top fram having any sagging issues and then down the road if she wants to use it as a quilt on a bed she could just remove the sleeve or leave it there.
Bye the way the quilt is beautiful