Timeline C: 2017-2020-ish

Five young mutants—Dani Moonstar, Rahne Sinclair, Illyana Rasputin, Sam Guthrie, and Bobby da Costa—are gathered at a mysterious medical facility operated by Dr. Cecilia Reyes, who is secretly working for the Essex Corporation to investigate their volatile powers. After Dani’s powers manifest as the ability to create powerful, tangible illusions out of people’s greatest fears, they summon a horrifying entity known as the Demon Bear, and the young mutants band together to survive and escape. (The New Mutants)
Side note: The New Mutants is standalone enough that it could exist in either Timeline A or C, as there are references made to the X-Men as an active team (as they would be at this point in either timeline) and Xavier’s school for gifted students. We’ve placed it in Timeline C as the movie uses archival footage from Logan to depict a vision of mutant children (specifically Laura Kinney, who we’ll get to shortly) being trained at other similar facilities, as well as the revelation that Reyes is backed by the Essex corporation, give it more connections to Logan’s continuity. Assuming it is set contemporary to its repeatedly delayed release, it would have to slot in at some time between the birth of the last mutant generations and the events that take place shortly before Logan. Speaking of…