Piza, Mr. Satan’s Manager, is Videl’s Mother

Little mention is made of Videl’s mother in the original serialization, other than that she died when Videl was young:

Not at all; dad’s been getting a little too cocky for his own good! Even if you take into account that he doesn’t have mom around anymore ever since she died, he’s been using the fact that he’s champion to fool around with tons of women! I would actually say it would be better for him to lose for once…!

The anime guide Dragon Ball Z: Son Gokū Densetsu even goes as far as to put in a separate entry for Videl’s mother, even though she is never seen (citing her as the likely reason for Videl’s good looks, as opposed to her father).

The situation was clarified during Q&A material prepared for the “Full Color Comics” release of the Dragon Ball manga in Japan, where — for the sixth volume of the Boo arc in 2014 — Toriyama noted:

Toriyama: Satan’s wife was a beautiful singer named Miguel!
“Since she was named ‘Miguel (archangel)’, during their marriage a big fuss was made about how ‘an angel is marrying a devil!'”

The name provided here was ミゲル (migeru), a reference to the Archangel Michael, fitting in perfectly with the stage name “Satan” and their daughter “Videl” (an anagram of “devil”).