Sprightly for a 72-year-old, Grandma Sparkles refused to leave the Wharf, despite the recent super mutant and raider incursions. She's protected by her deft hunting rifle skill and her family, who are out searching for mirelurk meat. She's tasted all kinds of critters and swears that mirelurk is the most delicious.
She occasionally says, "Y'all come back now, y'hear?". Every episode of The Beverly Hillbillies (as well as some episodes of The Dukes of Hazzard) ended with this very phrase.
The following is based on Fallout 3 cut content and has not been confirmed by canon sources.
Grandma Sparkle appears in a Form List whose only other entries are for the unimplemented Rock Crick hunters, possibly indicating that they are the "boys" who "are out hunting 'lurks."
A partially completed dialogue option in the Broken Steel add-on was to have allowed the Lone Wanderer to ask Grandma Sparkle what she thought of Split Jack's gang. Sparkle's reply is not present, leaving her opinion on the matter a mystery.
End of information based on Fallout 3 cut content.