Travel to where it is you’re asked to go, follow the objective arrow to find your target, then slay the beast. After that, return to the Companions HQ and report back to Aela . She will admit it was an easy job, but work is work. You’ll get 300 Gold for taking care of business.
This takes care of this quest, but as you’ll see they don’t let you pick any of the other two quests. Instead, when you ask for work, you are told that Skjor is looking for you again and a new quest will start: The Silver Hand .