I Can't End The Potion Making Quest

So I have a Problem: my quest book says I need to "Bring back Essren's Dusty Coat to the Assistant. But when I go to the assistant, he wants 8 red mushrooms from me. He also won't accept any mushrooms. Going down in the house does nothing for me as well.

I don't know how long I've had this bugged quest for, all I know is that its a level 15 Quest that I should have done ages ago (im actually think I may have completed it before) as I am level 48.

Is there any way I can either A: Complete it, or B: get rid of it?

 

The quest got a complete overhaul, so you had to re-do it. If someone has already killed him before he tends not to spawn again, so try switching servers. (from personal experience, not sure if it's right though) The 8 red mushrooms thing happens to me too, you don't really need to do it, it's just a bug in the quest I guess. All you need to do is kill Essren.