Sarada canonically is Sakura and Sasuke's daughter, just like it was confirmed over and over again both in the manga (in the last chapter of Naruto Gaiden) and in the anime (in several Boruto episodes):
Kai puts Elena in the coma in I'll Wed You in the Golden Summertime which takes place June 23, 2013. She does not wake up until just before May 2019, when Bonnie somehow finds a way of breaking the spell.
Marcel offers the jawbone to the Hollow in exchange for Sofya. Vincent's spell and Klaus' sacrifice goes awry when the Hollow's acolytes intervene. Freya and Hayley attempt to rescue Elijah while the Hollow leaves Sofya before attacking Marcel. Elijah is killed, giving the Hollow the power it requires to be reborn.
He's also now the most immortal character on The Originals — Elijah ripped his heart out, and he still survived. At the end of the season, Marcel bit Elijah and Kol, ensuring their deaths, and unseated Klaus once and for all.