Ensure that you've picked up Namira's Shroud from the Andas Estate Treasure Vault before beginning this quest, as it's necessary for completion. If you don't have it, Orlukh will ask you to go get it from the same room where you killed Tholer Andas. Once it's in your possession, talk to Orlukh in Anbarsud about the Daedric artifact. Being unsure how to unlock the power he senses within, Orlukh'll recommend taking it to Varos, so do so - the ancient vampire is in his usual spot in Romayon, adjoining Anbarsud, Forge.
Varos will confirm the artifact as the true Namira's Shroud (a powerful robe which activates a script that removes negative effects of vampirism, including shunning by the people, at the cost of a Constant Effect Drain Personality 30 pts), and asks to borrow it. Accept and Varos will disappear. Wait a full day until your journal updates, and then talk to Orlukh. He will suggest looking for Varos at the temple in Vhul, where the vampire apparently once 'lived' with his original clan.
Vhul is east of the Thirr River, the widest river on your map of Morrowind. It lies on the roads running between Old Ebonheart on the east side of the river's estuary, and the temple city of Almas Thirr (being some way northeast of the latter). Once there, enter the temple. Varos will be standing in the middle, and will apologize for losing track of time. He has searched the temple's records for any evidence of his original clan and now knows himself to be the only surviving member. Returning Namira's Shroud to you, he prepares to move to a new territory and asks you to inform Orlukh that he is now in charge. Before his disappearance however, he will teach you a power of his - Might of Varos, which cast a Fortify Fatigue 100-200 pts for 60 Secs on Self and Fortify Strength 10-50 pts for 60 Secs on Self.
Return to Orlukh to impart the news.