Translation:The girl comes back from school at two.
Right. For 2,3,4, you use singular genitive часа and for 5-20 the plural genitive часов - when the number is in nominative or accusative inanimate case as here. It gets more complicated when the number is in another case, see: https://www.youtube.com/watch?v=rUYzNgGy_HU&list=PLrIkLgUgjNHcq6hhO_btxkoFghnXeMZul&index=6
I added pm after 2 and it is rejected. Did not know in Russia girls return from schools at 2am as well...
Could приходит in this case also be translated at "The girl leaves school at 2?"
As some children sometimes do, they leave school but don't go home - so she wouldn't be coming back at two, she'd be leaving school and going somewhere else.