The Seastone Bluff can be found be leaving the farmhouse to the east. Once you hit the main road turn southeast and follow it briefly. There is a path that will branch off to your left (northeast). Follow this path the the Seastone Bluff.
There are plenty of shades, ghosts, and skeletons here to take care of your killing needs. Slay eight Risen Thralls, five Wailing Spirits, and five Doomed Spirits to complete the quest. Return to Bergen at Eliam Fields for your reward.