supercatboy

As a response to the "Vampire Knives" question:

No, they cannot be "taken" by other players during online play. To do that, they would have had to access the files stored on his device. Terraria has the great system of keeping worlds and characters stored in local files.

If you haven't already figured the whole "he hasn't figured out how to get pumpkins" conundrum. You can buy the seeds from the dryad NPC and plant the seeds anywhere wher grass can grow. However the pumpkins aren't directly renewable because they don't drop seeds when fully grown or otherwise. If he has a renewable source of money he should be fine I believe one seed costs 5 silver.