That's easy

If I was stuck in an island in the middle of nowhere, I'd bring these things:

1) A mirror - In case an Airplane, a Jet, or w/e comes, I can use the mirror and the next item to signal my presence in the deserted island.

2) Matches - To light fire for cooking my food, and using it to signal my presence

3) Water - To stay hydrated. I don't want to drink salt water. Food? I don't need food, I can get fruits on the island. Medicine? There's probably herbs and medicinal plants that can help me.