[@Ashgan]Modest street lights from outside. The candles still lit inside the space where the therapy 'session' was. Cellphone lights. Other than that, there is no electricity in this particular building. You'd definitely see the creature, movement and silhouettes, but maybe not details of the flesh, eyes, or possible hair. And of course, you can hear it. 

The emergency exit is at the opposite side of the hall, so it is not blocking a way out. It's no more than fifteen meters away from where the characters would exit the therapy session room.