It's not Without Warning, but that's a fantastic guess. I just saw it the other night and remembered this post. Without Warning has hunters, and a Predator-y alien (before Predator!), but unfortunately the ending is totally different. No, I'd have definitely remembered Without Warning's ending.
Another movie I've written off as a possibility is Demonwarp
. (DEMONWARP SPOILERS AHEAD!) It's also got guys with rifles wandering through the wilderness, and aliens. It even has an ending where the hero seems to get home and is "attacked" by monsters, in a scene right out of Phantasm. But it doesn't have that scene I vividly remember so well: the guy sitting in his kitchen, thinking he's safe, when he sees his dead friend standing in the door/window, or at least what appears to be his friend.
I guess the search (for the legend of Boggy Creek) continues.