I agree with washing the quilt. It is best to use a front-loading washing machine for this -- much easier on the quilt than a top-loading agitator. Laundromats have these, plus dryers big enough to handle a quilt.
If she has access only to a top-loader, she can stop the machine during the wash cycle and hand-agitate (pushing quilt up and down in the washer water), then advance to the spin cycle. She would stop the machine again for the rinse cycle, hand-agitating before advancing to spin.
She should not use a home dryer if she has to cram the quilt to get it in; chances are there will be hot spots that could burn the quilt. An alternative to using a dryer is to lay out the quilt on a sheet and have a fan blow on it, turning the quilt maybe twice a day until it is completely dry. If drying outside, the quilt must not only lay on top of a sheet but should also be covered by a sheet to protect from sun fading (and bird droppings!).