To people who didn't understand:
MC and young Hanada went through bunch of time shenanigans to "fix" timeline, and make MC's mother an idol/star again as she was meant to be. That caused her 'most precious form' to revert, but the author went with "branching timelines" idea of time travel. This means that the current time line is where MC's mother is in her normal form, she met her husband when they were young, they got together and everything went as it was meant to be. However, since Hanada also time-traveled, something got messed up during her time travel and after what some unknown amount of time she returned to the current timeline except stuck in the same "precious form" as MC's mother used to be in. She still remembers MC, and he seems to be remembering her now while the rest of the world has forgotten about the "Back to Sisters" crew (MC's mom, his teacher and Hanada).
I assume (no spoilers - haven't seen the raws yet) that MC will visit her, which will cause her to revert back to normal form. No idea if she and MC will get together though.