Your options here include fighting a runner and a small horde of 3 zed, or Stay Down watch them and fight them anyway. if you choose to stay down and then fight them, you fight two a small horde of 4 zed and a runner. Searching the corpses doesn't provide any reward.
Next, if you have a rope, you can get into the tree fort. If you do not have one, you can still get into the tree fort by searching and finding a pallet.
You hear a "soft scraping" inside the tree fort. You can Call out or Go Inside. Going inside without calling out shows that the scratching noise is coming from something too small to be human. It ends up being a squirrel nest upon further inspection.
Searching the tree fort afterward results in finding some food and water, with you concluding that they simply flew the coop when the zombies showed up. You are unable to get the rope they had used to "pull a Tarzan", and you leave.