Barbie Berth--: Looks like you have a real problem with her parents names Patrick & Mary McCarthy from Cork around 1900. There would be many hundreds like that. The only good news is that all civil records in Ireland are now being digitized and you can start looking on line for marriage license's with their names.
I also suggest you consider getting her death certificate from the state records, for the actual date, and search local newspaper records for that city to see if any male McCarthy ancestors (ie: brothers) are listed, and if so try to track them down via civil or catholic church records. If successful have any currently living male McCarthy descendants join the McCarthy DNA Study. This may help in locating where in Co Cork they came from. Good Luck as you will need it.