You will probably need to contact the company directly to determine what forms they need. Further, there are other questions that are not answered with the details provided such as whether you are a named beneficiary or whether it goes to his estate, whether there are other beneficiaries, etc. Further, although I am a Washington attorney, it is my understanding that the Small Estate Affidavit in California is for use where the total probate value is under $150,000. If the retirement, bank account, and other assets go to his estate, the total may exceed the allowable amount. I would suggest you contact the company from which the retirement will be paid to find out what documentation they will need to distribute the funds to you and any other recipients.