I believe that you would have to refer to your state or local ordinances. In Indiana (or at lease the county I am in), the rule is 2 persons per bedroom maximum. Hope this helps.
Nicole, just a note that on one of our Fair Housing events, our speaker was saying in instances of a very large bedroom, you may not be able to limit it to 2 people. Sounds like this would not apply to Monica's situation as it is a small studio, but I thought I would let you know about that particular situation.