I'm so sorry for your loss. You and your grandchildren will cherish the items made from these scraps as no one else could. They are special to you, and you should embrace them as a special gift from your dear grandmother to you. Have no guilt! You've both given so much to others through the years -- her with her scraps and you with your charity quilting -- that you both deserve to enjoy this last bit of scraps as a gift of love and memories between the two of you.