She emailed him last night:
Keith this is a courtesy email, just wondering what happen, it's the 26th of May,2016. And your 21 days have expired. I didn't receive anything from you...
If I don't hear anything from you by May 31st, 2016. My only option is to go to Small Claims Court.
He mailed her a letter and a check for $500 last week. Sent it registered mail. She is not getting any of her security deposit back, but is getting her pet deposit back.
If she doesn't have it by now, either the post office messed up (highly unlikely - our post office is really good in this country), or she gave Keith a bad address.