K.M.
I freeze casseroles every month. The ones that freeze best are with noodles or biscuits on top. Or since she is a vegetarian meatloaf and potatoes might be a good option for her. That way she can still eat the potatoes. Mashed potatoes and party potatoes freeze well.
Another vegetarian option for a freezer casserole:
layer cheese stuffed ravoli (already cooked), cottage cheese, spaghetti sauce and mozeralla cheese. My family loves it and it is so easy to make, freeze and heat up.