Confused about the anime ending
What happened to Walpurgisnacht?
In season 3 of the anime, the amusement park uwasa was destroyed, so Walpurgisnacht resumed its route towards Mitakihara. Touka and Nemu tried to go after it to continue the Magius plan, but all the magical girls cooperated to defeat Embryo Eve. Then Alina Gray went berserk, Touka and Nemu sacrificed themselves, then Iroha and Yachiyo dealt the final blow.
All this time, Walpurgisnacht was still going to Mitakihara and no one from Kamihama seemed to go after it. That means the 5 Mitakihara magical girls fought it alone. Mami was severely weakened at this stage after being merged with an uwasa, so there's no way they could have beaten it.
However, in the epilogue, the TV news reported that the supercell (i.e. Walpurgisnacht) has dissipated. We also see Homura triggering her time travel magic, implying that Madoka died, but she (Madoka) couldn't have wished for the undoing of the magical girl system in this timeline since everyone was still a magical girl in the end.
So, what actually happened?