my solution for this would not be great but it works for me 
What you can do is :
1. Make two global propertie in main.qml say bState and selectedFileName.
2. Handle the onStatusChanged signal in page A, and if your page's status is 2 , that means page is activated so check for that status inside onStatusChanged.
3. when you pop page B set the global property bState to true and assign selectedFileName with the actual Filename selected in Page B.
4. Lastly just use bState and selectedFileName in Page A.
Sample Code on Page A:
Code:
onStatusChanged:{
if(status == 2 && bState){
use selectedFileName here
}
}
I hope you understood what i want to say, again this is not a perfect solution but a workaround