The contract for Morvud goes under the quest name Contract: Missing Son and can be located on the notice board in Rannvaig which is on Ard Skellige. (Main isle) It can also be obtained by speaking directly to Odhen whom is also located in Rannvaig.
After accepting the contract head over to the ruins of Kaer Nyssen which is south from Rannvaig, upon arriving here you will find Morvudd which turns out to be a fiend. Fiends are relicts so lube up your sword with relict oil and go to town, durring the fight the screen will black out and the fiend will run away, simply use your witchers sense and follow the blood trail to find the fiend again, kill him and examine the corpse in his lair.
Once thats done you can return to Odhen to turn in the quest.