Path #1
Second night - PSL and Liar block Mental, but Knight and Vlad complete their actions - meaning Mental is not one of them.
Third night - Reaper kills Mental, then Doppelganger kills Nebula, and Chief Doctor heals Mental - meaning Mental is not Reaper, Doppelganger, or Chief Doctor.
PSL, Board Games, and Waifu are eliminated for obvious reasons.
In total, Mama, Father, and Monster remain.
Path #2
In the same way, we determine Fragment - Mama and Monster.
In the first night, the Mafia blocked Fragment (mind games?), but in the third night, they killed Mental, which hardly looks like a cunning plan by the Mafia.
Therefore, Mental and Fragment each have only one role left, right?