That is so cool that you two found each other and that you both have materials that you don't use and can share with each other.
If you really think your yarn isn't as great a gift as her fabrics were to you, then maybe you can use some of the fabrics that she sent and make her a nice warm quilt and send it back when you're done. This way you still save grace in how you feel, and she gets a nice quilt that she will always have to remember you by.
It's a share thing!