Completes her redemption arc by fixing the "mistake" of sealing the One-Tail inside Gaara.
Because Chiyo is low on chakra, Naruto offers his own to fuel the technique. This allows her to complete the jutsu at the cost of her own life.
This episode is widely regarded as one of the most emotional in the series, focusing on the ultimate sacrifice of Lady Chiyo and the revival of Gaara. Key Plot Points
After retrieving Gaara's body from the Akatsuki, Lady Chiyo uses her "One’s Own Life Reincarnation" (Kishō Tensei) jutsu to bring him back to life.