There are a couple of notices for the Mohill family and this relates to that family.
Irish Independent 6th August 2002
John J McGowan, Yonkers, NY husband of the late Mary and son of John and Ellie McGowan, Hill St, Mohill, August 2nd 2002.
Searching John J McGowan brings up a notice on Legacy.
Perhaps, if your friend has a memorial card for the John from Cork and is also related to the Mohill family, it might be a son of one of the brothers.