It seems everyone is going to take some type of blade and mostly a firearm or other blade but what about boiling water? There is hundreds if not thousands of diseases that will either put you in very bad health or possibly kill you if you don't get your water to a "rolling boil" (that is all you need, no need to take it past that because once the water reaches a rolling boil as long as you let it cool it will be good to drink).
The main thing you have to keep in mind is the following:
1. You can live 3 minutes without air (but you can't exactly take air with you right?)
2. You can sometimes only live 3 hours without shelter (like if it's to cold, bad weather, etc)
3. You can live 3 days without water
4. You can live 3 weeks without food
So to me the most important 2 things to take would be the following
1. Cooking Pot (I have a big 3.5L one that works good for boiling up a good amount or water or cooking food)
2. My Khukri (it is good as a drawing knife, chopping (about 90% as good as a small axe), cleaning game and defense
Of course it will be tough to clean small game with such a big knife, but you can always make tools with the Khukri to make cleaning smaller game.
Remember the rule is, if there is a tool that makes the job easier you make it.
With this I could boil water, make shelter, make traps to hunt game and hopefully find a piece of flint to start a fire or make a bow drill from a limb, shoelace/natural cordage to start a fire.
If you have ever seen snowshoes and solitude in there they live as primitive people accept they took there food (the only other thing they took was a stone axe or 2) for a year and there main problem was they got guardia which put them in a weak state for months. And it is a lot harder than you think to make cooking pots and pots to boil water with only your hands and maybe a knife or axe because they tried but it took a lot or time, and work.