Having obtained all the items, return to Derfel who will give you the last mission.
You need to head to Onarach M4(12) and reconstruct the precious crown.
1 - Hendi
You will be aided by a woman going by the name of Hendi, who you will meet after entering the cave. Just speak to Fae and you will receive the item. Return it to Delfer.
Your last task will be defeating the bandits in front of the house.
With them dead, you will receive access to Derfel's treasury hidden behind the fireplace and finish the mission.
The Best Defence
Corporal Ivar, standing beside Tam's Wagon M3(3), will ask you to kill a bandit named Connovar.
He can be found inside the camp in the south.
Quickly kill the man and return to collect the prize form Ivar.
The Tinker's Daughter
Bardan Tam, lying beside Tam's Wagon M3(3), will give you a mission of retrieving his kidnapped daughter from the bandits' hands.
The girl can be found inside Caer Tosai in the south M3(4). She's waiting for you at the end of the tunnel, guarded by a group of bandits.
Caer Tosai map
1 - Julia Tam
Speak to her and afterwards return to her father to collect your prize.