For me, that very last scene with Paulie at his mother's place was a touching comparison of the two of them.
Here she is in her simple little room watching Lawrence Welk play happy little tunes, and outside the window was the simple beauty of nature-a breeze through the branches of blossoms. This compared to the ugly violent and complex life of Paulie the hood - it made me appreciate the simple things of life even more. And I think it did that for Paulie too. A return to mom and simplicity.
<-----I'M TOTES ROLLING MY EYES