I thought the "Son" part was part of their first names…
Japanese names are in reverse.
So Monkey is Luffy's family name. Roronoa is Zoro's family name… etc.
Do you know if Bulma's mother ever was given a name other than the misconceived belief that she was Mrs. Brief?
http://daizex.fanboyreview.net/viewtopic.php?f=7&t=12853
Bulma’s mother
Bulma’s mother is actually never actually named during the series, but in the DB Forever name pun guide, Toriyama says that if he had bothered to name her, he would have used “Panchy”, a play on “panty”/”panties”.
Toriyama Explanation: “Now that you mention it, she didn’t have a name, did she? Supposing I did name her, I would have probably used ‘Panchy’. Not ‘Panty’.” [DBF]
Source Spelling:: パンティー/pantii
Name Spelling: パンチー/Panchii