How does the son get the deed to his father's house after he passed away?

Dad started buying house in 1999. The previous owner passed in 2000. There is no deed on file with the county records. The house paid off in 2008. Dad passed away in 2017. Property taxes are still in pervious owner's name but paid by dad. Son has agreement of sale, as well as, all money orders used to pay for the house. There is no widow but the ex-wife is on the original agreement of sale. Divorce was finalized in 2005. Courts county is Santa Barbara. How does the son get the deed in his name? Is it possible? Quiet title action? Trustee? Is it an option to file and represent oneself in this matter?