You didn't mention where in Pennsylvania they lived and died, but if George died in Pennsylvania I suggest getting his death certificate from the PA Div. of Vital Records. It should have his parents' names and no you don't need the parents' names to request a death certificate.
His obituary might prove helpful especially if it lists siblings. I'm assuming they lived in Delaware County. If so then try the Delaware county Historical Society to see if they can help you.
The church they were members of may have info on his parents. His obituary might list what church he was a member of.