That mean that she has a severe mental condition, (bipolar disorder, major and chronic depression, severe eating disorder ect. ) she then has to demonstrate that the cat performs a service that helps her condition.

She allowed her bi-polar daughter with 3 kids to move in. 

After he left she was ok for a couple months until she went off her bi-polar meds and resumed drinking heavily and smoking crystal. 

In my town the property owner can be cited for "keeping a disorderly house" (party houses).

Send a notice to cease and cite disorderly conduct which is a legitimate reason for an eviction...Obviously you need to follow procedure notice to cease and if the behavior doesn't cease follow it up with a notice to quit and file for judgment for possession based on these grounds...Also add a statement stating nobody is allowed up on the roof!!!  

@Ginny WestThe tenant downstairs needs to be arrested for being "drunk and disorderly".

Drunk and disorderly conduct in public?

I'd be surprised if he allowed any disorder from the pets but I won't know until I look into it. 

ALSO, come to find out, this woman is clinical bipolar; the realtor tells us AFTER all is said and done.

.: Likewise, someone suffering from anxiety or depression would have one animal prescribed for that "disability".There are around 300 different codes in the Diagnostic and Statistical Manual of Mental Disorders.