Ideally, you should have your own land where you can grow food, where you can take water from the ground, you should have strategic supplies of clothing and other things necessary for the next 5-10 years. I think that this is quite enough to live well even in such a situation
Nah, it's not gonna work out in real life
Unless you also have a good company armed to the teeth and ready to use their arms if necessary. In a Mad Max scenario (which you implicitly refer to here) all your stuffs will be quickly taken by gangs of scavengers running away from cities, while you will be left praying for life with nothing left to live on