Ennodius camps out along a river, just west of Windhelm (at least during the afternoon that’s where and how I found him…). He’s there all alone, making this job a piece of cake. He’s also a weakling. Take him out virtually any way you want and loot afterwards (even though there’s nothing worth taking, I’m just in the habit of looting).
Now you can either do the LAST assassination or you can report to Nazir (I suggest doing the last one; be sure to save!)