The comments here are very dumb. I mean they're usually dumb, but they're extra dumb this time. What do you mean the outside world would have been better? The fact that the village got destroyed in the first place disproves that. It was a safe Haven for elves, much better than any other place on earth.
And obviously she wouldn't want to take care of her herself, both because of being a demon Lord and because of what happened with Orius.
It's easy to extrapolate most of the remaining answers to questions here. Why not check up on Nephie? Her very presence causes problems. She is branded as a demon. Check. Why this village? Why not any other village? This chapter mentions that other villages had apparently been destroyed due to her presence. It would have been the same fate regardless.