I Don't Know

Addison, a typical teenage girl (struggling with the confusing nature of human adolescents), seems to not want to fit in with the 'crowd'. Her school life is just perfect: being accompanied by her 10 closest friends and 1 best friend for the period of her high school journey. No boyfriends getting in the way of her single relationship status.
The petite district she lives in is now having a new family move in - just across the road from her. Strangely, her district is foreign to the sudden movement: only a sparse amount relocate there, every decade.
Having a history of social anxiety disorder has been a weight on Addison's shoulders, and her mum noticing the sudden change in the neighbourhood forces Addison to greet the new neighbours.
What happens to Addison? Does the overwhelming fear block her from going to the neighbours? Who are they and why are they there?