Press the Home button to return to the home screen, then start the Smart Baby Monitor app again.
If the home button does not work either, soft reset your iOS device by pressing the home and the power button at the same time until the Apple logo appears on the screen.
How nice!
I've got such situation few times per night. And I'm often awaked by screaming child but not by my iPad with your frozen app waiting me to reset it. I thought it's a network problems and even bought new hi-end router but my iOS devices keep freezing as they do before.
Seriously, guys, fix this bug it's absolutely unacceptable for kids monitoring devices.