First, I think she would have problems with her age but a recruiter would be a better source to tell you what the age limits are currently.
Second, I am of the opinion that a better choice of MOS would be a radiologic technologist as it would be a complementary skill.
Third, check out this page and see if these guys could provide some advice. http://www.osteopathic.org/index.cfm?PageID=mc_militarydos_today
Age shouldn’t be an issue.