For those of you interested in reading about cases of clemency, it is easy enough to go to the New York Times website (which now does free searches for articles going back to 1981- going back further requires access to an electronic database) and do a search for the three terms "clemency abuse women" for a number of articles to show up. I haven't found out about mass clemencies of over 25 women, but i do have some leads on information relevant to clemency in general.
My Google search of "law clemency women murder" gave me two very good sites. One of them describes the The Michigan Battered Women's Clemency Project. The other is a description of a legal case related to that project: click me. Both of these articles list Carol Jacobsen as a contact person for more information on the topic.
The second website has a reference to a journal article Jacobsen co-wrote in the Hastings Women's Law Journal, 2007(no.18). The title is: "Battered Women, Homicide Convictions, and Sentencing: The Case for Clemency". Though written in 2007, the article deals with the decades between 1968-1988. If you are near a university library, they may have electronic access to this journal.
Lastly, using the database Genderwatch (which is, unfortunately, not available at the New York Public Library, the Brooklyn Public Library, or the Queens Public Library), i found a 2004 article from the Berkeley Women's Law Journal (vol.19, no.1) titled: "Unlocking Liberty: Is California's Habeas Law the Key to Freeing Unjustly Imprisoned Battered Women?", written by Jill Adams. The article discusses issues of clemency, or reduced sentencing, for women who killed their abusers.