Undergraduate ‘programs’ for specific majors are generally not ranked outside of a few fields, primarily because the “undergraduate program” at most universities is a wide-ranging holistic liberal arts education. All three of these are excellent women’s colleges with opportunities in the biological sciences and research. They all also benefit from being nearby other large research universities - at BMC she can do research at Bryn Mawr, at Haverford or Swarthmore, or at Penn; at MHC and Smith, she can do it at MHC, Amherst, Smith, or UMass-Amherst; at Wellesley she’s got many good universities in Boston with biomedical strengths.
So I think she should also look at the environment as well. Which of these does she prefer for other reasons besides just biology? Do they have other academic offerings she might be interested in? (The Five Colleges has a Culture, Health, and Society certificate, as well as a Biomathematics certificate program. The Bi-Co has health studies. Wellesley has a Health and Society minor.). What about the social environment? Because of their consortia, there may be more opportunities for co-ed socialization at Mount Holyoke, Smith, or Bryn Mawr than Wellesley - which may be good or bad depending on her preferences. The Pioneer Valley is an intellectual, college-student-dominated region; the greater Boston area also has a strong academic vibe. Bryn Mawr and Wellesley will offer a more suburban experience with easy access to larger cities while Mount Holyoke and Smith are farther away from urban centers.