I am also gluten-free (well, allergic to wheat), dairy-free and peanut-free, and there are many good places to eat. Disney is the easiest place in the world to visit and have safe meals when you have allergies
I use this website to help plan (
http://www.glutenfreedairyfreewdw.com/dining-resources/menus/). I browse the menus and see which restaurants have something I think I'd like to eat. Then I always note the dietary restrictions on my reservations, I ask for the allergen menus when I check in, and sometime I ask to speak to the chef if I have concerns about what I want to order. At the buffets, the chef will walk you though and identify food that are/are not safe, and if you have concerns about cross contamination they will bring you a plate of food from the back to eliminate that risk. At a quick service, you will have to wait longer for your food as it is prepared in a separate part of the kitchen.
Ragland Road has gf fish and chips. There is also the option to get gf fried chicken at 50s Prime Time if you contact the restaurant ahead of time to let them know you want to order it (email to special diets:
https://disneyworld.disney.go.com/guest-services/special-dietary-requests/) and or stop by the restaurant before your reservation time to let them know. I have also enjoyed meals at the Tiffins, Hollywood Brown Derby, Flying Fish, The Wave, Kona Cafe, Captains Grille, Be Our Guest, and others. However, I was very disappointed at Tokyo Dining, but that was the only place I would not return. With a little bit of homework you should be able to pick out some places that will work with her taste and dietary restrictions.
As far as snacks are concerned, Erin McKenna's Bakery in Disney Springs has great gf/df treats! And there is an alley-friendly kiosk in Animal Kingdom called Terra Treats.
