Regarding the death of Catherine Duignan McKeon, I also found a death certificate for a Catherine McEwan (maiden name Dagnan) in 1893 in Edinburgh. My ggf Patrick moved to Edinburgh and married there before emigrating to the US. I also found a Catherine McKeon (no maiden name, b. 1817, d. 1896) at Cloonmorris cemetery in Leitrim; hard to tell if there are cousins or just unrelated Duignans with the same name.
Thanks to everyone for all of your assistance.