This quest is not available in game.
Kilix the Unraveler in the Pit of Narjun wants you to enter Azjol-Nerub and destroy 6 Nerubian Scourge Eggs.
Throughout Azjol-Nerub, the scourged nerubians carefully nurture eggs that will soon hatch, providing them even greater numbers.
It would do little good for the caverns to be cleansed of the undead that stain them if these fouled eggs were left to hatch and take their place.
As you explore the expanse that was once Azjol-Nerub, be sure to clear our ancient home of any scourge eggs you find.