I'll be there myself in a couple of weeks. The museum is just off 59 (Sligo to Ballina road) in Dromore. I was their last about 8 or 10 yrs ago. Has a replica of a small An Post office from turn of the century, a chemist shop, etc.
Maybe your Grandmother knows any of the Lynotts from Culleens. Anyway, good luck with your search.