Your client can still put a stop payment on the check (if the check bounces, it will then be this woman's problem).
You can sue this woman for breach of contract. The damages would include both the return of your client's money (if the check goes through), plus the cost of placing the stop payment, plus any additional damages "proximately related" (directly related) to her actions.
Your client may have an independent cause of action (if he wishes to pursue a claim individually), for "fraud in the inducement" - which would make any contract he entered with her "voidable" (the injured party can void or enforce the contract at their option), as fraud is an intentional tort, he would also be entitled to punitive damages.
(Given that this woman is using funds to pay rent, I would recommend exercising discretion here, as getting a judgment vs. collecting on one are two different things, you likely will collect (wage garnishments, bank levies, property liens), but it can take some time).
Fortunately, the amount is less than $10,000.00 so you can take advantage of small claims court: http://www.courts.ca.gov/selfhelp-smallclaims.htm