What a nice neighbor you are! I think I would just call her and in a friendly manner ask how's she doing with the quilt she was making; was she able to use any of the fabric that you gave her and if so how much of it. Then I'd ask (in a friendly manner) if she still had your address so she could send payment.
(I have to keep saying "in a friendly manner" because in reality, I'd be a little ticked off myself! I have to keep my evil twin Skippy from coming out LOL).
Maybe she was just busy with the wedding and the quilt and forgot. Or maybe she's a user. Either way, you are a great person. I've had that happen here on QB: someone asked for blocks or patches cause they needed help. I sent stuff and never heard from them again or saw a completed project. I almost stopped donating. Don't stop helping fellow quilters--even if only 1 out of 10 is truly in need it's worth it. And YOU can sleep at night.