I understand your will to make her something that will keep her warm and show her what she means to you.
That being said, I don't think a rag quilt is the way to go. They shed unbelievably in the first few months. Or rather all the flannel (with batting) ones that I've made, do. I don't think you want to create a mess for her to clean up while going through this.
There are plenty other easier quilts to do. Check out this post for other ideas. Good luck.
http://www.quiltingboard.com/t-41091-1.htm