Tiffany Harper is an alumnus of Central City High School, the daughter in-law of Kathy Meyers and the wife of Freddy Meyers. In the original timeline, she was the only survivor from the Prom Night Slasher.
In 1989, Tiffany was the most popular girl in school. Encouraged by some classmates, she invited the nerdy Freddy to be her date to the prom with the plan to humiliate him. She would be the only survivor, aka the Final Girl, when their classmates were slaughtered in the original timeline. She would get killed by Freddy's mom Kathy, now an Encore, at the reunion 15 years later.
In the new timeline, after Freddy showed up wearing a nice suit, thanks to his Fairy Godmother Nora Darhk, Tiffany began to have second thoughts about the prank because she was not only taking a liking to Freddy, but falling in love with him. She tried to spare him from the prank and was angry when her classmate Brad revealed the plan to Freddy, who stormed off in shock and devastation.
But Nora convinced Freddy to return and show everyone his true-self. This resulted in Freddy giving an incredible dance performance, with help from Nora using her magic to make the pile of trash disappear while busting it like a DJ. This allowed Freddy to fully win her heart. Tiffany, Freddy and several of their classmates left the prom where they encountered Zari in a limo and were attacked by Freddy's mom in a mask while she was wielding a big knife. They were saved when Behrad Tarazi blasted Kathy using the Air Totem resulting in Kathy being arrested. 
In 2004, Ray and Nora attended the reunion, and saw that Freddy and Tiffany were now happily married. Freddy thanked Nora for giving him a great life.