My wife requested an early 401k cash out due to financial issues. She was living in AZ at the time of the request. When she received her 1099-R forms, it had CA as the state deducting the taxes. She had been a legal resident of AZ for 7 months when she requested the cash out. She informed the 401k administration of the change in address but they messed up. They now tell us that we need to file a form to request CA for the improperly withheld taxes. Anyone know what tax form they are talking about? They didn't know themselves.

First you must find out to which state you will report the 1099-R income. It is not Arizona if you were not living in Arizona when you received the payment.

If you think that it is not CA income, then you will file CA tax return to claim the refund. You may need to attach a statement why it is not CA income and attach tax return of the state where you have reported this as income.