A quick question about him and his mother.

I just saw this movie once so I might have missed something, but was the old lady who moved in next to him his mother? I wasn't sure because he called her by her first name 'Louie/Lou' (if I'm not mistaken) so I was wondering why he doesn't call her 'mother' like he did in the beginning of the movie. At first I wasn't sure if it was even his mother because he seemed pretty rude to her.