Ive killed all nightkins but cant end the quest!
What to do, hardland is also dead!

And ive seached the entire basemant 5 times!

If you killed all the Nightkins then the quest should be over. You sure you didn't miss one?

I don't recall if you get an update. Try going back to Bright and see if he will thank you for clearing the basemant.

There is one named Nightkin. His pip on compass is green until you confront him. His room is near where you should of found a holed-up ghoul.