It's real easy to get into the city from Islip. Check out the Long Island Railroad website at http://www.lirr.org. There is a station in Islip and also in Ronkonkoma and your cousin can take a cab from the airport to the train station(s) (there may even be a shuttle bus to the station - check with the airport).

The number of trains going into the city would of course depend on the time of day and day of the week. I know someone responded that there were few trains out of Ronkokoma; this is really odd since Ronkonkoma is a major hub for the railroad. Anyway, on the site you can see that there are trains running all day into Manhattan (Penn Station)as well as returning well into the evening.

Hope this helps.

regards, vanessa cutchogue