I had the Sargent Genealogy, but had not had time to compare what it said about Emma/Emmar with the information she provided. I was surprised that the 1895 publication gave the same date of birth for Emma that she had. There are two images that are a part of this post. The first summarizes Clark's information and the second discusses his children.
The children of Clark are right in terms of sex and number, but it is also interesting that the date of birth matches precisely the one that Emmar gave in deposition.
Emmar Osenbaugh deposition, 24-25 Oct 1918, Emmar Osenbaugh, widow’s pension application no. 772,537; service of John Osenbaugh (Pvt. Co. H, 7th Ill., Inf., Civil War); Case Files of Approved Pension Applications, 1861-1934; Civil War and Later Pension Files; Department of Veterans Affairs, Record Group 15; National Archives, Washington, D.C.
Sargent, Aaron, and John S. Sargent. 1895. Sargent genealogy Hugh Sargent, of Courteenhall, Northamptonshire, and his descendants in England by John S. Sargent ... William Sargent, of Malden, New England, and his descendants in America by Aaron Sargent. Somerville, Mass: Sargent