For the past five weeks, Kelsea Ballerini has been co-hosting ABC’s musical variety show, Greatest Hits, with Arsenio Hall. Each week, Kelsea and Arsenio highlight a five-year musical period between 1980–2005. On Thursday night (July 28), the “Dibs” singer got the chance to take the stage and show off her stuff during the 2000–2005 episode.…