This page of our game guide to Assassin's Creed Odyssey describes the following quests:
Onwards to Phokis
The quest takes place as soon as you make a decision about Nikolaos. When you decide what to do with your main character's father, go back to your ship. Talk to Barnabas and decide it's time to visit Phokis. The quest will be over. Reward: +2700 XP.
The Wolf's Fate
It's time to inform Elpenor about the effects of our expedition. You have to get to Phokis and then go to the man's headquarters. You'll start a dialogue - whether you killed Nikolaos or not - there is going to be a clash anyway.
The man will run away - defeat the guards and start searching the house. When you collect some evidence, the quest will end. Reward: +3750 XP.