> * Grow some of your own food in a garden.

This will get you a handful extra meals, assuming the ideal case where everything was fully grown, harvested, and preserved before the incident. It's one thing to have a village harvest & jam cycle for the seasons, it's another to need to be prepared for the situation to change overnight, all alone and with only a home garden to work with.

You're better off using the money, time, energy, etc. to buy provisions that are immediately and near-permanently useful without the variability, climate sensitivity, and labor intensity of gardening.

You would be surprised how much you can grow in a small space. But also small additions of fresh fruits, vegetables, herbs, and greens to your long term stores of rice, beans, and preserved foods can go a long way towards making those foods more pleasant and making up for some of the nutrients which are either not present or destroyed by preservation processes. In situations of major food shortages even a little bit goes a very long way.

And also, gardening is a high quality activity for you and your family at any time. It feels good eating a little bit of what you've grown, and there are lots of things that are either not possible or rather expensive to buy but simple to grow.

In a lot of places you can get permission to have your own water well. You may not even need to filter it.