Not knowing her level of playing, "safety" is somewhat hard to judge. Have a look at Susquehanna University. They accept a pretty wide range of students to their BM program, from some who would be competitive at top conservatories to others who are not quite so talented, but nonetheless have a love for music and are willing to work hard. They do have an extensive core curriculum, but it appears that over half of the distribution requirements can be filled by taking specific music classes - see Susquehanna University - Academics: Central Curriculum Courses
for the complete list of requirements and courses that can be taken to fill them.
Although it is not a safety unless she is a phenomenal organist already, I assume that Oberlin is on her list. It sounds like exactly what she is looking for. They have a great organ department, the town is very small (but there are many activities at the school to make up for it, e.g. about 500 concerts and recitals during the eight months school is in session), and the requirements outside of music are fairly minimal and very flexible. She will have to take one course per semester from Oberlin College. One of those has to be a freshman writing course, but she can be exempted from that requirement with a decent SAT or ACT score. The rest of the courses can be pretty much anything she chooses, including courses that are partially or entirely about music, so long as they are offered through the College or the Experimental College (ExCo) rather than the Conservatory, there is room in the class and she has taken the prerequisites. Check out the website at Friday Night Organ Pump
and the article at Oberlin Alumni Magazine :: Winter 2005-06
to get a feel for the organ department there.