anyway school. Not just the couple weeks FEMA recommends. Look at Puerto Rico and imagine your power grid taken out for months by a rogue nation.
#1, as said, has to be WATER. Many could live a month without food, but elderly people in a hot climate with the power out could die within hours. It's what would be driving many people into the streets within a couple days when they should be staying safe and comfy at home.
Minimum 1/2 gallon per day just for drinking. We've learned that those thin bottles of cheapest water in the supermarkets leak over not much time. Need sturdier containers, like sanitized orange juice bottles, 50-gallon barrels if can afford, etc. The problem of course is storing it, but no less than a month's supply. Serious business. We have room to store a fair amount, but if we didn't we'd also buy a 100-gallon bathtub storage bag that'd sit in its box on a shelf until needed, $25-35. In most municipalities and emergencies, I'm guessing there'd be time to fill it before the water stopped running, but rushing home to do that ASAP would be imperative. Could become illegal to draw that much water at once within short order.
As for food, we also just lay in more of what we'll eat and use over the year anyway. I cook a bunch from scratch so have lots of spices and lay in extras of the condiments and other ingredients I know we'll use. We buy extras when they're on sale, which makes it FRUGAL.
Our big basic food stock is of dry rice and beans, which combine to make a complete protein and will last 2-3 years stored properly. Their vitamins are reportedly basically gone after 5, though they'd still provide other nutrition and fill the stomach. I'm not thinking of a 5-year disaster but rather of just being able to store them in a tight plastic container in the basement or under the bed and forget about them that long. Also salt. Both, btw, could be eaten without cooking after being soaked in liquid, and some of even old beans should be able to sprout.
Multivitamin as part of the food supply to stay healthy. These last about 2 years before starting to lose efficacy but are still good for some while after. Walmart's Equate line will supply one person about 3 months for $3-4 or so, so a year for each person, plus some to give away?
Beer could last several months if my husband didn't know it was closer than a trip to the store.