Hello Kevin,
The "School's Collection" at the dúchas.ie website provides a handwritten account and transcription of Dargoon and the surrounding townlands in the Civil Parish of Inishmagrath, County Leitrim.
The account, entitled, "My Home District," was collected by Nora McHugh, who interviewed Patrick McHugh of Coollegreane. I'm not sure the date that "My Home District" was compiled. The Irish language name for Dargoon was Dearg Dún (the Red Fort). See: https://www.duchas.ie/en/cbes/4605939/4604153
And to add to the census kindly provided by Roger McDonnell, attached is an Ordnance Survey Map of Dergvone from the Tailte Eireann website. The map is from the 1829 to 1842 time period.
I also found a copy of your mom's birth record at the free irishgenealogy.ie website, and can send it to you in a follow-up reply if you don't already have it.
Best Wishes,
Dave Boylan