Is Taylor Swift's music for Mom's and Daughters?! In this case, 100%. Kelsey posted a video on TikTok of her and her mom Christie singing "The Best Day" by Taylor Swift and the video has already been seen over 2 million times. Christie has non-Hodgkin lymphoma and is entering the terminal phase of the disease. She's been battling it for 15 years and her daughter Kelsey wanted to memorialize their presumed last Christmas together. See their duet to Taylor's "The Best Day" HERE