I don't really know when he died. If he died before the 1906 earthquake..it's hard to get any paperwork. I know more about the female side the Dillon/Greeley.
I don't know where in Ireland Patrick came from. I know the Dillons cam from Athenry, Galway. He may have met Margaret in SF or on the East coast. She was single and with her parents in 1860 Waltham, Mass and then married (they were living with her parents) in 1870 SF. I can assume they were pretty newly married as their children were yet to arrive.