Meredith is NOT the benefactor. She is being used by him. It is PETER. Remember it goes back to something in season 1. Peter bit Lydia in season 1 & she did not turn into a werewolf. He used Lydia to bring him back to life. All the clues revolve around Lydia. Allison: her friend, Aiden: her lover, Derek: Lydia brought him to the place to bring Peter back to life, Ariel: What Lydia's grandma called her. Peter knew she was a banshee, he found out about her past and used Meredith to decipher the code and make the list. By the killing of all the supernaturals he is getting back his power. He once said that he is the only Alpha. He is manipulating Kate and he told her that he wants power. He was not surprised she was alive. He knew the connection between Kate & Derek. He manipulated her to make Derek weak. So he would not kill him again. He set up the heist and everything else, that way know one is thinking it is him.