You made a wonderful heartwarming find.
I would try making several packets of paper towel or fabric(it has to be able to breath) and fill them with backing soda. Them tuck them in the folds of the quilt. It works in the refridg,shoes, ect. and should work in the quilt with out harm. If some of it gets on the quilt just shake it out. I know that charcoal works too but I would be afraid it would escape and get on the quilt!
Good luck