Back Rent Collection From Vacated Tenants

[Jonathan Dickerson]

Short version: 4 adults (family) rent our Townhouse on a 3-year lease. "Bob-The Son" gets hooked on heroin, vacates the property, returns to steal everyone else's stuff to pawn for drugs, gets arrested and goes to jail. "Susie-The Daughter" vacates the lease a year early because she's 'so over' all the drug drama (but does not communicate with me that she's left). Remaining 2, "Carol and Jim-Mom & Dad," are unable to afford the place on their own (both on disability) and need to leave. 

Not counting late fees, they owe $4k in rent from May-July. Their plan is to move out now and repay the missing funds after they receive a settlement from a slip-and-fall they had after the HOA didn't properly maintain the parking lot which turned into an ice rink last January.

I'm trying not to gouge anyone going through a REALLY rough time, but what is the process for collecting the back rent from Mom & Dad and/or The Daughter? What's the process for making it known that The Daughter vacated the property early? Is this a small claims court issue or something else?

Any/all thoughts guidance and professional recommendations are welcome. Happy Monday!