I can't open the website right now, so no input there, but how old is she? Would she be willing to spend a day (or a weekend) with Gramma and help make the quilt? If you could get her cutting the shirts, adding the stabilizer, and maybe doing the piecing, it could speed the process. And, if she just wants it quilted to some fleece, no batting, that can be a pretty quick process.
Bonus, it would give allow some quality gramma/grand-daughter time and she'd start to get familiar with a new skill, which could be a big confidence boost if she decides to tackle more sewing/quilting crafts in the future.