If I were you I could not bear to give away the last box of scraps from my grandmother to someone who couldn't care less about the sentimental meaning of the fabric. I would take your grandmother's fabric and make something for yourself and your family who would understand and cherish the meaning behind the fabric. If you're really feeling guilty about having fewer charity quilts to give then use some of your fabric to make some charity quilts but I don't think that's really necessary.