My husband has celiac as well. Dinners can be easy if you remember nothing breaded. Potatoes and rice are always safe goods as well as vegetables. No macaroni- unless you buy gluten free which is expensive.
Good luck. Enjoy your visit.
PLEASE talk to her mom - cross contamination is a very real threat - there is a level of "clean" that needs to occur to prevent it in your kitchen. You may not be able to make her anything that is safe to eat since you use all the above in your kitchen.
Talk to her mom/dad/caregiver - don't guess at recipes and how to make them safely. Her health is on the line.
@rabarbar I agree!! Talk to Mom and Dad. Never guess on these recipes. A good friend of ours ate no meat and when their daughter went to a friends house and the mom served spaghetti w/ meat sauce. The poor little girl ended up in the hospital. So be very cautious.
Don’t struggle just serve Meat and vegetables and fruit easy peezy
Porkchops or steak with baked potatoes and green beans or corn
Chicken and vegetable stir fry serve over rice or noodles
Burgers or hotdogs and fries or roasted potato wedges
Chicken with fried rice and broccoli
Bbq chicken with potato wedges and salad or coleslaw
Spaghetti and meat sauce or meatballs
Roast beef chicken or pork with roasted potatoes and carrots or corn
Meatballs in golden mushroom soup with boiled potatoes and carrots
Beef or chicken stew
Fish and fries with coleslaw
Baked salmon with broccoli and rice pilaf
My daughter has similar food sensitivity.
Applegate gluten free chicken tenders are delicious. Try to find a Whole Foods they will have allergen free options. Gluten-free bagels with non-dairy cream cheese spread is one of my favorites. 
 Mission gluten free tortillas filled with ground beef and vegan shredded mozzarella and grill in a pan. Just a tip for anything gluten free you want to get it really crispy because the lack of gluten will cause it to kind of just fall apart in some cases fyi.
I joined a bunch of gluten-free dairy free and vegan Facebook groups for recipes too.
 gluten-free substitutes are pretty easy to find for any recipe so I would focus on looking at recipes that don’t have dairy or eggs 
Another one is rice paper egg rolls! There’s no egg in it lol tons of good recipes. And lots of Asian recipes use rice flour instead of wheat flour so that’s helpful. And NO SOY SAUCE just get coconut amino‘s it is gluten-free and taste the same pretty much.
@teshan thank you! The nearest whole foods or Aldi is 2hrs away from where we live. A local grocery and Walmart are our options. I will see if I can find some of these and maybe order what we can and have it shipped.
I'd reach out to her parents and see if they have any suggestions. You can make peanut butter balls with peanut butter, oats and vegan chocolate chips that are delicious.
@jgodeaux this was diagnosed 2 weeks ago and she was already a very picky eater. Basically everything she would eat she now can't. Mom is struggling and I have always been the nutritious focused one so this is my way of helping show there are other options that taste good and are good for them.