These kinds of threads are like a "how long is a piece of string?" question. It's best to think of it from your personal context. It's going to be contingent on all sorts of things like budget, space, dietary requirements, taste preferences, family number, garden space, personal self control levels (not to raid the chocolate stash 
)
Imagine you are housebound for a few days (family member has infection and you all need to stay in). What food would you ensure you have in?
Also imagine you are going camping for a few days (with no cool box facility) and only a small camping stove. What shelf stable/long life food do you take with you?
Combine these two lists and you'll cover two main bases that are likely to be affected. Shortage of supply in the supermarkets and hairy situations there as people have fisticuffs over the last pitta breads and celery sticks on the shelves. In case of energy shortages, you also have long life and easy to heat up food.
Have a look through your current stocks, previous till receipts, meal plans, shopping lists etc to help build a masterlist of things to prep.
I would say, as a first layer of prepping go for nutrient density. Meat, fish, vegetables, eggs, dairy etc. You deffo need to put more protein on your list. Cover fresh, frozen, tinned, jars and shelf stable sachets.
Secondarily, stock up on caloric density as a fall back. Flour, sugar, vegetable oil etc. Less than ideal, but will see you through.
Don't forget household cleaning/supplies... washing up liquid, laundry powder, kitchen cleaner, bleach, bin bags, cleaning cloths etc. Soap/detergent is always scarce and in demand in a crisis. Also personal hygiene... soap, shampoo, sanpro, deodorant, toothpaste etc.
Pet stuff... food, flea treatment, poo bags, cat litter etc.
General useful prepper stuff... hand cranked radio, batteries, torches, USB lights, portable fold out solar panel, USB battery pack to charge phone, tea lights, matches, water purification tablets etc.
Don't forget first aid and medical stuff... a good first aid kit and basic OTC meds like ibuprofen, imodium, insect cream, savlon etc.