I forgot to do the "Return of the Wolf Queen" quest before I bought a house and became the thane of solitude. So, even though "Assist the people of Haafingar (5/5)" has been completed, it annoyingly shows up in the Journal under misc. quests (I'm guessing that's the reason for this bug). What is the console command to remove this? Please help because a soiled journal irks me like a thorn :)
Just complete another assistance quest in Solitude, it should update and then the quest will disappear from your journal.
The UESP fix you mentioned in the comments by using the console may work for you, but it did not work for me so I had to do it the other way.