Under Probate Code §§ 13100 - 13115, your husband can make a declaration that your father-in-law's estate is of small value, below the Probate Code threshold for opening Probate. You can find a form of declaration by going to your local law library or searching online.
As far as the check from the management company, you may need to return the check and request that they make it payable to your husband, since he is the legal successor. Then, your husband should be able to deposit the check by presenting the bank with the declaration form.
Please note that, while I am a lawyer, I am not your lawyer. This information is for general educational and informational purposes only, and is not legal advice. You should review your particular situation with a qualified lawyer of your choosing.
I agree with Mr. Buckingham. If the apartment complex refuses to accept an affidavit under section 13100 (a "small estates affidavit"), you can take them to court to force them to accept it. If the Judge determines that their refusal to accept it is "unreasonable", they will be required to pay both your court costs and your attorney's fees. Usually if you let the company know that they'll be paying your fees, they become much easier to deal with.
The information you obtain at this site is not, nor is it intended to be, legal advice. You should consult an attorney for individual advice regarding your own situation.
Mr. Buckingham and Ms. Brewer are right.
Following is a link to the Los Angeles Superior Court guide to Transfer of Small Estate without Probate which provides a sample of the declaration as well as more detailed information about the requirements and process: www.lasuperiorcourt.org/probate/pdf/transferform.pdf
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