I will guess that aidin nanny kill her self because it was aidin last assessment/exam to become full assassin and her nanny don't want aidin feel guilty of killing her.
damn, i was thinking it was going to be more along the lines of grief. it sounds like they're using the actual nannies daughter to have her be a nanny to aideen, so i though something was going to happen to her daughter (or something already happened and she figures out they were hiding it from her) but she couldn't safely do it except in aideen's company/room









I thought he wil say "are you lost baby girl" hahahahahahha peace everyoneヾ(☆▽☆)