Later on in the film, after Tony becomes a werewolf and murders multiple people, he tries to call Arlene. The authorities are with her waiting for this call, but Arlene shows guilt in this scene as she doesn't want to do anything that will risk the well being of Tony. Arlene is also critical to the plot for being the first reason Tony becomes a werewolf. She didn't do it intentionally of course, but takes the first step in leading Tony to his eventual demise. Arlene suggests to Tony that he should go see a mental health doctor. Initially Tony declines, but after yet another violent outburst, he agrees. He goes to see Dr. Alfred Brandon, the doctor that Arlene suggested. This is important for it is Dr. Brandon that tests his experiment on Tony which turns him into a werewolf, and a killer. Tony isn't necessarily the villain of the story, for Dr. Brandon is the most vile character in the film, werewolves are archetypally killers and villains, and Tony fits this conception. This archetype of a murderous werewolf is seen in "The Werewolf's Daughter", as the werewolf in the story is a vile murderer.
It isn't known whether or not Arlene knows she played a part in the transformation of Tony. Yet in the scene with the phone call and the police with her, Arlene shows guilt and angst which could have been derived from her potential knowledge of what happened with Tony and Dr. Brandon. Guilt is a powerful story telling tool, and Arlene's is incredibly important to the narrative of "I Was A Teenage Werewolf".
Family Works - https://extension.illinois.edu/familyworks/teen-05.html
The Werewolf's Daughter Story - http://www.pitt.edu/~dash/wolfdaughter.html