The correct answer is Worf, who had his birth father, Mogh mentioned many times, but whose birth mother was never mentioned nor shown by name
All TNG principle characters who've ever had parents mentioned by name
Will Riker - Mother Betty
Beverly Crusher - Father Paul Howard, Mother Isabel Howard
Ro Laren - Father Ro Gale, Mother Ro Talia
In which episodes of TNG were these established? I don't recall any of them being mentioned in the series or films, which is the body of knowledge this "game" is limited to.
Except for Riker, they are briefly glimpsed in Conundrum
and in The Next Phase
. That is according to Memory Alpha, but the two episodes did show lots of information for those with good eyes or a good DVD player.
Right. Beverly's & Ro's appear in crew manifest files. A file was done for Riker too, but actually got cut out of the scene. However it is still listed in the Star Trek Encyclopedia. So technically, someone could have answered him, because of his mom too