Pick a line in chapter 25 which ties in to the mockingbird theme?

“Then Mr. Underwood's meaning became clear: Atticus had used every tool available to free men to save Tom Robinson, but in the secret courts of men's hearts Atticus had no case.” (Chapter 25)

Tom Robinson was a bird caught in the cage of bigotry. He could not defend himself and Atticus did everything he could to breech the hate and bigotry in the hearts of the jury: Atticus just could not get around that to protect a kindly innocent man. 

pick up THE line sorry i corrected myself their is a specific life in chapter 25