He need to find a way to get back in status under an H1B or any other work visa as soon as possible.
As for future Green Card applications, Section 245(k) of the Immigration Act enables a person who is adjusting status in an employment-based category (whether on the basis of a labor certification or in one of the special Green Card categories that does not require a labor certification or job offer) to adjust, even if s/he has been out of status or worked without authorization for less than...
If the Father is her illegally, his option to become a US resident are more limited and will depend on when he entered the US, how he entered (legally or not) and if any legal documents were filed for him in the past.
As for his son, he could file and petition for his father when he turns 21. But the filing alone will not grant his father legal status. It will start the process to obtain his immigrant visa.