Food (or a way of getting it), same for water and medicine. Some form of shelter is good, but not the utmost priority, and a simply tree or something to sleep under can be good enough. I wouldn’t immediately go for guns, as there are usually nonviolent solutions to conflict and bringing in a gun only raises the stakes and makes it more likely for people to get hurt.

The knowledge you know in you mind has the potential to be just as valuable, if not more so, as physical items you have. Knowledge on how to catch food, and build shelter, can be more useful that simply owning some cans and a basement.