Mary Denio b. 1814 d/o Joseph L. Denio

My gggg-grandmother was Mary Denio, she married Lewis Freeman. Her death certificate
lists her father as being Joseph L. Denio b. in Canada. It lists Mary as being born in Canada on February 11, 1814. She died on March 14, 1911 in Ferrisburg, Vermont. It
does not list her mother's name. This is as far back as I've been able to go. I'm not sure if Denio is the correct spelling or not, I have several ancestor, who's named were changed by phonetic speller. I'm searching all options. Thanks in advance.
Nickie