The movie has no specific music soundtrack, except for occasional music in the surrounding, probably to emphasise the seriousness of the life the main character leads - a life without joy and happiness.
Your whole life you've been thinking about your dead son! Your dead, dead, dead son!
Ana has an ID number (called "JMBG" in Serbia) of a baby that was officially alive for only a few hours. That means that it took just a few minutes for the baby to be assigned an ID number immediately after birth, but in reality this procedure lasts much longer.