Have her host family google quilt shops in San Francisco and make sure to call and make sure they are still open.
http://www.yelp.com/search?find_desc...rancisco%2C+CA
I heard that New Pieces in Berkeley is supposed to be great. I have not been there but my friends have. It is a bit of a drive but I'm sure the folks wouldn't mind.
Fabric Outlet is in the Mission District which is close to Excelsior. It gets good reviews.
Britex is a 4-story overwhelming piece of architecture that is filled from bottom to top with ALL TYPES of fabric. It's kind of overwhelming.
If they ever take your daughter on an outing, have her google quilt shops for that area and see if they can stop.
I hope she has a great time and does some successful shopping for her mom.