Shaws is getting better and better with their gluten free/peanut free selections within their special "health food area" in the middle of the store. I only know the Concord ones and she would be better off at the one up in the heights by the mall and not the one just off 93. The section is bigger there.
There is a Food Co-op in downtown Concord which I rarely go to but seems good. I need to go more. The bakery even makes some allergen free foods as well.
http://www.concordfoodcoop.coop/products.html
The best in the state IMO is the Co-op in Lebanon. Though quite a drive for her. Just across the way from Dartmouth Hitchcock Hospital. Lots of local foods, organic foods, bulk foods, special diet foods, natural local meats, unbelievable amount of local baked goods, etc all mixed in with the regular Sure Fine foods. Its so worth the drive. Its the only place I have found that has rice yogurt for example.
http://www.coopfoodstore.com/
You do not have to be a member to shop at either co-op.