If you haven't done so already, try doing a Google search for her birthdate/year with place of birth and words like adoption or adoptee.
If all else fails with the paper trail, you may want to look into autosomal DNA testing. I'm an adoptee, and I found my birthfather's family that way. As time goes on and more people do DNA testing for searches and general genealogy, many of these brick walls will be broken down that way.