My Irish Hopkins roots are in Mayo. I'm doubly blessed with the Hopkins name. My grandparents were Hopkins cousins. Yes, it is frustrating with the given names of John and Mary. Do you know where in Mayo your grandmother traveled? Are there any photos from Ireland; letters?
There's a large group of Irish Hopkinses around the Castlebar area. That's where my Hopkins line is from and my Hopkins cousins live.
What does the US census say about your great grandfather's birth? Is this where the confusion comes in with various birthplaces?
What about Mary's brother, Francis? Have you checked out his Social Security info? His baptismal certificate? Does Francis have any sons?
My mother was born in Pittsburgh in 1908 and I was looking at the info on the baptismal certificates of her older cousins and couldn't believe the info on them. One actually gave County Down as the birthplace of the parents (which of course doesn't help you).
The names you list are not familiar to me but contact me off list to see if I can help you better.
Nora Hopkins FitzGeraldIrishcolleen45@aol.com