Cook a serving of rice (bag of rice is quite cheap for how many servings – I’m talking Asian rice bags). This is about $25 for 15 pounds. A serving is 90 grams meaning 1 bag is 75 or so servings. So $0.33 per serving.
Buy whatever discount can of soup you can find. Dollar store is a great option. Heat that up and mix into the rice. You now have poor mans risotto. $1.33 per meal and you can buy a bunch of different flavor soups to change up your meals. You get carbs, protein, veggies all in 1 meal. If you want to be extra frugal you can split the soup into 2 servings. So $0.83 per meal.
You’ll be hard pressed to find a cheaper meal.