I have a distant cousin, named Mabel Roxy Howell, who is also descended from my great-grandfather, Joseph Howell. I wonder whether she could be the same as your Mabel? Her parents were John Henry Howell and Ada Blanche Crow. (Henry's parents were Joseph L. Howell and Louisa M. (Wescoat) Howell; Ada's were George W. Crow and Julia Bone Crow.)
According to my information, Mabel Roxy Howell was born on June 20, 1890. Then there is some conflicting information: I have her as of July 1, 1954 (listed as a survivor in her mother's obit), married to one Alfred E. Livington or Livingston and living in Wayne, PA.
There may be an explanation for the apparent divergence. Your Mabel could be my Mabel's niece, for example. Or she could be the same and married twice.
Where did the Howells mentioned in your album live?