At least where I’m from, Clark is considered to be a more “prestigious” school than Muhlenberg. It’s also on the Colleges That Change Lives list, which is quite the honor for not-so-famous colleges. I’m deciding between a couple of them myself! As long as she’s comfortable with Clark and would be happy going there, I think Clark may be your winner!
You may also want to check out this thread for a more legit compare and contrast of the 2 schools: http://talk.collegeconfidential.com/college-search-selection/1270650-muhlenberg-college-vs-clark-university.html