Mokou lost her Cards 滅罪「正直者の死」 - Forgiveness 'Honest Man's Death and/or 時効「月のいはかさの呪い」 - Limiting Edict 'Curse of Tsuki-no-Iwakasa' because Nitori changed destiny so that in the new history Mokou didn't kill Iwasaka (the man who was supposed to destroy the Hourai Elixir and was murdered by her in canon, as evidenced in Cage in Lunatic Runagate) and thus she didn't have a motivation to ever create the spells in the first place. [/infodump]
Just in case anyone was wondering