McManus
I'm also the granddaughter of a McManus in the US. He was survived by one son, but that son had no males to carry on the name.
Many with this name were also sent to live in the prison colonies in Australia during The Great Potato Famine. I've researched and found that two McManus couples were even married on the transport ships to Sydney. Many a McManus were sent to "the coffin ships" for petty crimes of stealing food. This way they were able to survive the famine.
Anyway, I don't know who is related to whom as it seems to be a much more common name than I thought.