you should start eating the rice and beans, perhaps one a week, just so you get used to how to prep them, and condition yourself for that kind of sudden fiber change in your diet. And, honestly, you want to rotate stock anyway in case it takes longer than you think before you need it.
But, more importantly, get a bunch of cheese blocks. Rice and beans sucks without something yummy. you can fill your "crisper" drawer (the one that no one puts any veggies in) full of 1 lb bricks of cheese, they last for months, and you rotate through them anyway.
If the fridge goes down, the cheese doesn't go bad instantly either, it just gets kind of oily. but, if you are hungry, cheese is a huge bonus when combined with rice and beans.
You might also want some peanut butter, its cheap, stores forever, and has a good balance of oil / protein / eatability.