At the request of SE_Kahuna over on reddit I am making this post. After completing floor 50 of Palace of the Dead and having already completed the Corpse Groom quest after finishing Tam-Tara Deepcroft (Hard Mode) the quest titles The Nightmare's End still was not showing up for me in idyllshire regardless of the quest becoming available for everyone else in my party upon completion of floor 50. This has since been resolved as it seems it was caused by a small spout of server lag on Siren from the flood of people in Quarymill for the dungeon entrance. All I had to to was restart the game and leave the area for a little while and then teleport back and the quest appeared. Thanks again to SE_Kahuna on reddit for suggesting I post this here.