This needs to be a well thought out procedure. Make sure you have at least one day s worth of food that takes little or no preparation. Remember a can opener and utensils needed. Provide a way to heat food if possible. Try to select foods that are easy to store and that will last.
Water is essential.
A gallon of water for each person is essential. If water is not available, eat very little or no food. Salt and pepper will help food items be more palatable. Include a lot of snack type foods such as nuts, jerky, nutrition bars, raisons, gum and hard candy. Lists of other supplies are many and varied.