So I was doing stuff in Windhelm to get the house and, of course, I did Blood on the Ice. I did it without confronting Wulfwhatever and so, the murderer struck again obviously.

Now, I am doing the Dark Brotherhood for the first time and I just talked to Muiri in Markarth. She gives me an optional task to kill Nilsine Shatter-Shield... However, Nilsine was the victim discovered after imprisoning Wulfy. Will I still get the bonus? The quest leg itself is not listing as completed, even though the character is already dead.

FUUUUU!!!

Nothing else can be said. :S

I suppose I could resurrect her just to kill her again...

You can actually Try it.

put "resurrect" in console and try. Else..

Try console commands.

showquesttargets. Page up and down until you find a
DB04 (or DB03, DB99.. whatever. DarkBrotherhood Quest)

Then.. "Getstages DB(somenumber)"

will sort some numbers from 0 to 255.

and.. setstage DB(somenumber) (some number you think could be the optional quest target you desire.)

Oh man. This is turning out to be a hilarious set of coincedences here.

So I go back to res her, but her body is gone. So I grab her REFID and teleport her body to me outside the town gates of Windhelm. Res her, wait for her to turn her back and begin to slit her throat as she's opening the door, and before the execution animation finishes, she disappears on the otherside of the loadscreen door and I have to kill her again. XD

[censored] has died 3 times now LOL

lol I did the db quest first, so when I had to get the key to hjerim, it just led to an empty marker. Turns out tova kills herself after you kill nilsine... bugged quest ftw

wich is a shame cause if i remember correctly,that quest is a prereq to be able to marry Muiri,one of Skyrim's finest young maidens.