Jill Taylor (Patricia Richardson) on "Home Improvement": I always thought that all of the males in her family, including her husband (Tim Allen), were immature and needed some old-style discipline, while she frequently struck me as being exasperated with them.
Dr. Beverly Crusher (Gates McFadden) on "Star Trek: The Next Generation": Lots of "Trek" fans apparently felt that her teenage son Wesley needed to be 'taken in hand' by her, perhaps via some sound corporal correction.
Martha Kent (Annette O'Toole) on "Smallville": She normally couldn't have effectively whupped her son Clark (Tom Welling), of course, but I could envision her paddling Lana Lang (Kristen Kreuk) and/or Chloe Sullivan (Alison Mack).
Jadzia Dax (Terry Farrell) on "Star Trek: Deep Space Nine"): She engaged in Klingon mating, which apparently involved equal parts of loving and fighting, with Worf (Michael Dorn) no less, so she clearly could've delivered a wicked ass-thrashing--perhaps to youthful Dr. Julian Bashir (Alexander Siddig), who was arguably a bit too persistent in attempting to seduce her during DS9's first season.
Ezri Dax (Nicole DeBoer) on "Star Trek: Deep Space Nine": She was physically rather small and somewhat lacking in self-confidence to begin with, but I occasionally like the concept of an unimpressive-seeming female 'going against type' and turning out to be a firm disciplinarian. She was a counselor (psychologist), so presumably she could've administered a convincing therapeutic seat-smacking if necessary.
[I'm playing on a technicality with both Jadzia and Ezri, since their purely Trill personas seemingly weren't mothers, but the Dax symbiant undoubtedly had earlier maternal experiences which they would've shared while it was occupying their bodies.]
I'd also agree with another commenter's choice of Ann Romano (Bonnie Franklin) on "One Day at a Time"...

--C.K.