Just got some new information about Margaret. First is her death certificate:

Margaret E. Ketchie
Died at 10 p.m., 5/9, 1935 at Concord, Cabarrus County, North Carolina of coronary thrombosis (2 hour duration)
Born 11/29/1854 in Cabarrus to Monroe Isenhour and Barbara Goodnight (both born in Cabarrus County), she was 80 years, 5 months, 10 days of age
A white female, she was a widow
The informant was Wade Cline, Concord, N.C.
Burial was at Oakwood, 5/11/1935

From that I did find her in the 1860 census for Mill Hill, Cabarrus County, NC:

Mag Isenhour
In the household of Barbara Isenhour, Mill Hill, Cabarrus County, North Carolina
5 years old, female, white
Born in North Carolina

Still cannot find out which Overcash she married before marrying my great-uncle, Ben Ketchie. Any help on that or going further back with Monroe Isenhour or Barbara Goodnight would be appreciated.