basically anything that can be heated in the oven, and eaten with one hand if necessary! (i hate micro reheated food - it never stays as hot, and you can only heat it once - if it's in the oven, you can heat it that way, then micro if absolutely necessary)

lasagne can generally be cut with a fork - pasta bake is easy too. slow cooked food in gravy/sauce that can be reheated easily.

we did curries etc frozen with rice already mixed through. not quite as appetising as fresh, but simple just the same.

i was lucky when DD was born as DH was working away, and this sort of food was second nature for us, and always in the freezer. we had those little tin trays with meals stored in them - he could reheat in his little portable oven thing in the truck, or i could put them in the oven myself at home. it was very simple stuff but very tasty and simple enough to manage. i'd probably aim for those sort of trays if you can - simple, single serve (in case mum and dad want different meals or something), and the tray for reheating is able to be thrown away without adding dishes for clean up.