A batarian refugee needs the Pillars of Strength to improve his people's morale. Find the pillars in the Kite's Nest and return them to him at the Citadel refugee camp.
Listen to the batarian preacher who is standing near the entrance of Cargo Hold C in the Docks: Holding Area. You can also acquire it if you scan the planet first. This second way of acquisition is possible even before the Docks becomes available on the Citadel.
Travel to the Kite's Nest cluster. In the Harsa system, scan the second planet named Khar'shan. Head back to the Citadel and talk to the batarian who will reward you for your efforts and thank you for restoring faith to his people.