The attacked happened just after 1 a.m. in the 6700 block of Sylmar near McAvory Tuesday.
Witnesses told police it started as some kind of argument inside the home and spilled into the street.
Police say the son took that bat and beat his father over and over again in the head. The mother hid in a neighbor's yard.
She was loaded into an ambulance but is okay.
Detectives do not know what the argument was about. They believe there was a disagreement about a broken down car at dinner that carried into the night.
The name of the son has not been released. Police say he is 29 years old.
He lived with his parents.