Don't get Newark Penn Station confused with Manhattan's Penn Station - two different places.
PATH doesn't go to Manhattan's Penn Station, it goes to 33rd Street and then you walk a block or so. Unless things have changed a lot since I lived on 28th Street.
Since he's heading to (NY) Penn Station, you might want to have him get onto the LIRR and save the folks from driving into the city?
EDIT: in other words, when he gets on the bus or whatever at the airport, make sure he asks for either Newark Penn Station or New York Penn Station - whichever route you decide. You want to be aware that at Newark airport, Newark Penn Station might be the default Penn Station, when you might really want NY Penn Station.
Also, I am reminded that there is a local bus at Newark Airport that goes to Newark Penn Station, when you can take the local PATH to NYC. This is evidently the least expensive way to get into the city from the airport - but remember, I've never done it so be sure to check it out if you think it's an option.