One of the biggest issues with GMO food is the allergy cross-over. Because genes from nuts, fish, soy and other highly allergenic plants/animals are used in the to give the need seed the desired characteristics, they can trigger serious allergic reactions in people who had no way of knowing the food was dangerous or even which food it was that caused it! If that wasn't bad enough already, it will certainly only be worse in a grid-down situation where medical care is limited at best.
For example, have you considered the need for feminine products? What about canes, walkers, and manually operated wheelchairs? Pets need food, crates, and toys to keep them occupied while the rest of family members are recovering from chaos. It will be impossible to cover every contingency but be aware of what those needs are now then prioritize those that you deem most important.
Precious Metals – Investigate this for yourself, but I find the arguments and historical track records against fiat currency and the current rumblings of Government wanting to take care of your investments for you very compelling. Gold is easier to transport with the high cost to weight, but you might have problems cashing a gold coin for a tank of gas. Silver is where I have chosen to invest in precious metals.