Just because a female has the same last name as her father does not mean she is unmarried. A relative of my had the maiden name of Mattie Huls and her husband (unrelated) had the last name of Huls. It is always possible that a woman marries a man who has the same last name as she does.

© Michael John Neill, “Genealogy Tip of the Day,” http://genealogytipoftheday.blogspot.com, 12 Jun 2012.

Note from Site Admin: One reason could be that this is not her maiden name but she had a prior marriage.
In my own family, the woman’s husband died and she married his brother.
It might not be a maiden name.