Complex sentence: After the Nogitsune's defeat, Scott, Stiles and Lydia go back to their lives, mourning their close friend's death, with Isaac and Chris leaving Beacon Hills together to help each other cope.
Split into simpler sentences: After the Nogitsune's defeat, Scott, Stiles and Lydia return to their normal lives mourning their close friend's death. Chris and Isaac leave Beacon Hills together to help each other cope.