This quest is undoable and completely bugged. I managed to to the first one after several weeks (needed 2). The assassins simply never popped. That's WEEKS. I took the quest for a repeat and it asked for FOUR to be killed. After more than a month, only 1 had popped. Per recommendations, I cancelled the quest and and picked it up again, but this time it's asking for SIX to be killed. At that rate, it will take a year to finish one quest. Something is badly wrong.
