It was hard to me to hit the "like" button for what I consider one of the absolutely worst of the worst episodes in the entire series. I'm surprised you didn't like "Miracle Man" from season one, although I wrote a lengthy comment under that video of yours, but this episode, titled "3", is almost universally reviled among fans. There is a very very small percentage of people who enjoy it. The episode is completely misplaced, Mulder is very weird, the story is confusing, and there's lots of mediocrity from start to finish. To answer your questions, well, they were obviously some kind of vampires or supernatural beings, or else the man wouldn't have burned from the sun and later came back. It is implied they are vampires. At the end, she manages to kill him because she tasted the blood of a believer and also "took a life", or was about to take a life, in this case her own. Something along those lines. I never managed to figure the whole episode out because, as I said, I think it is terrible. So I hit the like button not because of the episode, but because of your video, lol.