There's no way of knowing!
There is no factual record of Mary Meachum’s likeness or image anywhere. While drawings exist of her husband, John Berry Meachum, no known description, likeness or image has ever surfaced to date of Mary herself.
Then who is this?
This image, catalogued in the Library of Congress, was a photograph taken by W. E. B. DuBois in 1899 or 1900 and it was in an exhibit of portraits of African Americans in Georgia exhibited at the Paris Exposition Universelle in 1900. This is not (and could not be) Mary Meachum.
Once when the Mary Meachum Freedom Crossing Celebration event here in St. Louis was about the World’s Fair, we used some of these historical images in a collage for the event. Someone (not sure who) must have mistaken this for Mary Meachum and spread it around online.
So if you see this image somewhere, please help correct the facts!