The needed mobs are next to each other (here: the farming area southeast to the Anontican Station Griffon Tower ( -19, 0, -770 ) Copy/waypoint -19, 0, -770).
Kill 10 undead farmers. ( -12, 0, -768 ) Copy/waypoint -12, 0, -768 After this, kill An undead explorer there. They are placeholders for farmers and settlers (step 4)