My Sims haven't killed her yet since all the recruits just turned around and left. Chickened out? I saw one video where someone's sim made friend with Mother. If you get a good friendship with her, ...
By attempting to communicate with her many times will eventually allow your sim to befriend her. Increasing the relationship will only unlock two abilties no matter whether it has been revived or not. The abilities are asking for a bizarre fruit (once all red is cleared) and gifts (once your sim is friends with her). Abiltiy to set the weirdness of StrangerVille comes after you first revive her. Reviving her will provide a huge boost in relationship. That means you have to first defeat the mother plant. Sims you recruit should stay during the fight. If you don't bring any of them with you to the secret lab, they'll appear next to the mother plant once you start the fight. You must defeat her to save the town. If you defeat the mother plant, bizarre plants will disappear (even those planted in gardens). If you want them back, revive the mother plant with one bizarre fruit and request weirdness from her.
I'll put my video under the next spoiler tag so it won't take much room.
