Question: At the end, who was part of the travelling circus that Mattie didn't like?
Answer: It was Frank James, brother of Jesse. He didn't stand up as she approached. She was offended by his lack of manners.
Answer: Rooster Cogburn. She considered him a legendary lawman, like Wyatt Earp. She felt bad that he was reduced to being a sideshow attraction in a circus.
Answer: Most likely, Redridge is giving Solara a chance to escape Carnegie's regime. At this point, he knows he's dying, but perhaps still wants the best for her. Remember, he had a crush on her the whole movie (blocking her while she was getting Eli's canteen filled, bargaining with Carnegie for her before chasing after them, even asking Eli nicely to give up the book after the gunfight in the house). I think it may also have been used as a self-redemption moment for one of the bad guys.
Jason Sieberg