If her intention is produce tops, don't worry about the backing until the top is finished. Choose the pattern, or a focus fabric then the pattern, fabrics, then start cutting the pieces. If she plans on quilting them while down there then by all means pack the backing and batting as well. But I have never started a quilt by choosing the backing first (although sometimes one of the fabrics I use in the top is also used for the backing, at which time I already have the pattern and top fabrics chosen then I just buy MORE of the backing fabric).