Question: what episode does abby die in the 100?
Answer: In "Adjustment Protocol," Abby becomes a Nightblood to protect Madi. As a result, Russell Lightbourne wipes Abby's mind, effectively killing her and turns Abby into the new host for his wife Simone. Simone is floated by Clarke shortly thereafter, killing Abby's body as well which is left floating away into deep space.