The Crusaders' plan could have taken a rather macabre turn if things had played out differently.
I guess it's lucky that it's a children's show.
Now, I don't dislike Babs, she was pretty okay in the end. However she was totally the jerk in the episode (not that I'd want her to be murdered of course). She was the one who was bullying the Crusaders, despite their best efforts to be friends. Their final 'prank' was just an act of reciprocation, and could have easily been avoided by Babs simply not being a jerk. I don't see why the Crusaders felt responsible.
Disclaimer: The author of this comic does not endorse murder. Please consider any homicidal actions carefully.