If the damage were isolated to just the large hole in the aqua, I'd say put a piece of aqua under the hole, and hand stitch the patch in place using a buttonhole type stitch. But I can also see damage in the small pieced squares. That makes me think it's just too large of a job. How about retiring the loved quilt, and help her make a replacement in the same pattern/colors! The repairs would be stronger than the remaining, and I think that with continued use the old quilt would just continue to disintigrate and then would be a total loss without even a shred of anything except a memory. This looks like a new years project for you! Sara