You are saying that one of your grandmothers, Charlotte Louise Melon, m. a Taft and the other, Gladys, d. ca. 1988 in Mass. as a Taft. In other words, both of your grandmothers m. Tafts!?
I find a Gladys Taft who died in Worcester Co., Mass. in 1988 (b. 29 Jul 1892). I can look up her death record next week to see who was her husband.
If you have, or can obtain, further bits and pieces, contact me at NeilBTodd@cs.com