Explanation: Parks was taken to jail. She asked for a drink of water but they refused. Finally she was allowed a call home. Her mother was terrified when she heard Rosa was in jail, worried she’d been beaten. Raymond promised to come get her right away, but she knew it would take awhile because he didn’t have a car and needed to find a bail bondsmen. Two iconic pictures of Parks being fingerprinted (seen here) and of her mugshot are not from this arrest, but rather from her arrest in February 1956 during boycott when she was arrested along with other boycott organizers for their role in the boycott. But they are regularly mis-attributed to this arrest.
It depends on your relationship with him/her. Probably say something like, "Thank you for being an inspiration", or "Thanks for being so patient". Anything you think you want to say.