A little game for you

A twenty-something girl walks down the street. She has a shaved head and her eye are full of the misery and darkness of her past. The girl knocks on her old teacher's door. It's been years since she has seen him. An old(ish) looking man opens the door....

The girl recognized him immediately.
Mr Thompson? said the girl, tears brimming in her eyes.
Yes, who are you?
It's.. it's hannah She breaks down into tears and the man looks at her with worry and shock.
Why are you here?! He says, in a fearful tone. He, of course, remembers the girl as the student he used to teach. How could he forget her face, even without the manic expression that still haunts his dreams.
I'm... I'm sorry! I'm so sorry! The man doesn't know how to react, he can't forgive her, but it wasn't her fault...

What you have to do is guess what the girl is sorry for, what she did all those years ago.

she Stabbed the Old man Teacher guy!

or maybe she Stalked him?

Umm is there an acctttuuaalll Answer to thiss? Or is it juss Guessing? Lol

Maybe.. She's having a dream..
She's seeing her old teacher, and she killed him in real life.
She feels the guilt now, and this is her way of saying sorry?