Wood pigeon

Hi everyone we have a wood pigeon nest in our hedge, With one fledgling, I’ve been watching from far for about a week and have noticed that the mother hasn’t been back to the nest since yesterday morning, this will be its second night alone.

Im worried something might of happened to the mother and now this little fledgling is orphaned.
Do the mothers usually spend so much time away from the nest? 
I was looking for some advice on the best thing to do? 

Thank you