Can someone explain the ending?

Meldrum, the psycho priest, convinces Bernard that the murders of Terry, Vanessa and Meldrum's mother were done by Miss Brabazon due to her mad jealousy and undying love for him. He also convinces him that it's best to cover-up the crimes for the sake of the Catholic Church's reputation. After Bernard departs, Meldrum calls Jenny to see if she's home. When he learns that she is, he puts on his cloak and steps out into the night, obviously intending to kill her since she's the last person who has info that could incriminate him.

The message seems to be that authority figures -- and especially respected ones -- can more easily get away with audacious crimes simply because of their honored position wherein people naturally assume the best of 'em. It's similar to Nurse Ratched in "One Flew Over the Cuckoo's Nest."