About the photo, judge Tom Humpage, had this to say:
The photographer has created solitude using light which is unusual among this shortlist. I like the way she is staring into the camera so you know it’s a genuine facial expression rather than a fleeting tick the camera has captured. The young girl is singled out, which makes you think about what destiny has in store. Great composition – a shot to be proud of.
On Laura Cook’s photography website, she explains the context of the winning shot:
I was not given long to take this photograph but was drawn not only to the woman by the beautiful 6pm light that flooded her face but by the way she found peace in a crowd. Not always an easy thing to do.
In the MatadorU photography (and writing) programs, students are encouraged to submit work to weekly labs in which it is critiqued by faculty members. This photograph was submitted in one of the weekly labs where Laura received feedback. Learn more about MatadorU here. 
*Special note: MatadorU students Genevienve Hathaway and Stephen Chapman also made the shortlist. They are photos #4 and #5 in this slideshow, respectively. Congrats to you too!