Watch The 100 S05e13 1 -

Video logs reveal that Monty and Harper chose not to go into cryosleep. They spent their entire lives on the ship, raising Jordan and monitoring Earth's recovery. When it became clear Earth was a "lost cause," Monty spent decades cracking the files of the Eligius III mission to find a new, habitable planet.

Once safely in space, the group discovers they lack the resources to survive indefinitely on the ship. They decide to enter cryosleep for ten years, hoping Earth will recover during that time. However, when Clarke and Bellamy are finally woken up, they learn that have passed. Watch the 100 s05e13 1

Faced with imminent defeat, the primary antagonist Paxton McCreary launches a nuclear missile, destroying the valley and making Earth permanently uninhabitable. Video logs reveal that Monty and Harper chose