Inquirary On A Collins Missionary

I found some information concerning a Mary C. Collins that was a missionary to the Sioux. In a book titled “Some Things Are Not Forgotten: A Pawnee Family Remembers” by Martha Royce Blaine pg. 253 she writes in the notes section, “12. In a letter to Herbert Welsh of the Indian Rights Association, from M.C. Collins, 15 April 1891, she states that the Indians with Wild Bill Cody in Chicago have been reported as being in deplorable condition an “terribly neglected, and it is a disgrace that men can be so treated.” NA RG 75, “Documents relative to the Ghost Dance Religion,” Special Cases, no.188 roll 2.”

Another book makes note of her as well in a book called “Wild West Shows and the Image of American Indians, 1883-1933” by L.G. Moses. Moses sites Mary C. Collins as a missionary to the Sioux.

I am wondering two things. First of all how would I find out what denomination this Mary C. Collins was from and two is there any genealogy on her family?

Thanks