Morrowind:The Vampire Hunter

Quick Walkthrough
#Speak to Dhaunayne Aundae.
#Travel to Ald'ruhn and slay Ano Vando in front of witnesses in broad daylight (9 am - before 5 pm).
#Return to Aundae and receive the Aundae Amulet.
#Slay twelve vampires.
#Return to Aundae to receive access to the clan's cattle.

Detailed Walkthrough

Set an example
The Aundae Clan leader, Dhaunayne Aundae, at the bottom of Ashmelech, will ask you to kill a vampire hunter who has been exploring Ashmelech. Although you are given no name, you are told that the hunter lives in Ald'ruhn. Also, you are told explicitly to kill him in broad daylight with witnesses to provide an example to others. 

The Vampire Hunter
Travel to Ald'ruhn and ask around the Mages Guild to learn that the hunter is Ano Vando and is actually walking near the Mages Guild carrying an iron mace (the Light of Day) and an ebony shield (the Darksun Shield). Be sure to kill him during the day (9 am - before 5 pm). Though Dhaunayne Aundae says you need to be seen, it isn't actually required. When you kill him, you will receive a journal entry saying whether you did it at the right time. Note that although Vando's equipment is quite powerful, don't try to use it while you are a vampire as the items will do continuous scripted damage to you.

Attempting to use the shield will display the message: "You feel a searing pain on your arm as you equip the shield. A voice screams out in your mind, "This is not for your kind, Dark One."". 

Equipping the mace will result in this bit of text: "Your hand begins to blister and burn with the pain of a thousand suns. A voice echoes in your mind, "Never shall you wield this, evil thing."".

Return to be rewarded
Return to Dhaunayne when Vando is dead to receive the Aundae Amulet which will Recall you to the clan's headquarters.

But wait, there is more
Dhaunayne Aundae will then tell you that you might find further reward if you kill any 12 vampires from the other clans, Quarra or Berne.

Any vampire you killed before starting this quest will not count towards this task. Spare Berne and Quarra's lives until the right moment. If you kill any of your own clan during the quest, you will need to kill that many extra from the other clans. There is no journal entry to inform you when you have killed the necessary number of vampries; you will need to keep track of the number of valid kills on your own.

Return to Dhaunayne once you've killed 12 vampires to receive permission to use Vampire Touch on the clan's cattle to heal yourself (just don't kill them).

Notes

If you kill Ano Vando before asking about him in town and getting the corresponding journal entry, the quest will not update properly upon his death. Consequently, you will be unable to complete the quest and receive the Aundae amulet.

After killing Ano but before leaving the dialog window with Aundae, make sure that the "future rewards" topic is available, otherwise the next time you talk to her it will be permanently lost, and you won't be able to complete the "kill vampires" part of this quest.

While in Ald'ruhn, it may be a very opportune time to complete two other vampire quests: The Boy Who Would Be Undead and Shashev's Key. Due to the difficulty of traveling as a vampire, killing two birds with one stone while already in this town rather than completing only one quest and having to return here later is very convenient.

Quest Stages