I think a scrappy (perhaps a string quilt) with bright colors would be nice. If time and money would allow it, how about 2 twin size quilts. One for the grandmother & one for the grandson. If it is higher elevation & gets chilly at night, a medium loft would probably fit the bill. What a wonderful thing you are doing for the less fortunate. I would also sew a label into the quilt so it can be identified. By sewing it into the quilt, it wouldn't be easy to cut out. Please post what your final decision is & also I'd love to see pictures.
God bless you Rita.