That cash can be used for food and other necessities. Credit cards, debit cards, and checks might not be accepted. Pay them 3-4 months in advance. Get any and all agreements in writing. Cash-will be the best option here.
Nothing beats hard cold cash in an emergency.
Expect prices to go up. Second, use the food from the freezer. Stock the following amounts per person, per month. Canned juices, milk, soup. Keep in a cool dry area.