Sometimes the media scares people into stockpiling emergency food, such as by predicting a snowstorm (or more poetically, snowpocalypse), flood, hurricane or blockade. Even if the threat of being cut off from food and other supplies was real, so stockpiling would make sense, fear often makes people act irrationally: panicking stockpilers buy the wrong quantities of the wrong products, for example dozens of toilet paper rolls and disinfectant wipe packs.
The smart way to prepare for an emergency is to list the products needed (and only those) and then calculate the necessary quantities. For example, medical handbooks such as UpToDate specify the daily nutrient need for a person conditional on age, weight and physical activity. The quantities of foods that satisfy the nutrient need can be found for example using the USDA food composition database. To find the quantity to buy for emergency preparedness, multiply the total daily food intake of the people in the household by the likely duration of the emergency (plus a reasonable safety margin). Tallying supplies is just like planning event catering or consumables for a hike: the number of eaters times the number of meals. The same simple spreadsheet-based quantity calculation applies to other emergency supplies like matches, batteries, medicine, fuel.
A natural disaster may cause power outages and less frequently a loss of water supply. Therefore emergency food should not need cooking and there should be a drinking water stockpile in the home. Contrary to this common sense, irrational emergency shoppers sometimes buy instant noodles, rice and other foods that require hot water to prepare.
Of course, the stockpile of supplies for a disaster should keep for a long time. A minor and neglected aspect of emergency food is that it should not tempt the stockpiler to eat it at non-emergency times. The temptation of course depends on the person, but chocolate bars may be a bad idea, especially in a household with children or binge eaters.
The requirements of being non-perishable, edible without cooking and non-tempting are satisfied by for example canned food, milk powder, instant oatmeal, flour (despite being usually consumed cooked, flour and oatmeal are edible straight from the pack, in contrast to rice, dry peas, beans and cornmeal).
A minor consideration is variety in the food, which helps keep boredom at bay while waiting for a disaster to end.