Even though she lives in a cold climate, that doesn't necessarily mean that the interior of her apartment, house, or dorm is cold. I would ask first whether she has trouble keeping warm at night. You can do that without admitting that you're making her a quilt. For warmth, I think I would use one layer of wool rather than two layers of anything else. It's light, and it breathes. Flannel is already heavy, and I'm afraid that adding two layers of W&N would make the quilt very heavy and difficult dry when it is laundered. That might not be as big an issue if you're making a lap quilt, rather than a bed quilt.