You have the right spirit, but you may be getting ahead of yourself. Does your friend want a T-shirt quilt? Did her husband wear T-shirts? (Mine didn't.) A quilt from his dress shirts, or flannel shirts, or even something else might be more appropriate. Perhaps you could make her a quilt from your stash, just to say you care about her. I would visit with her and try to determine what she would like, what materials she has on hand (and what you can afford to make) before planning out a quilt.