Taffy Tales
It takes a little before Mom scenes begins, but then it does it goes for the domination / degrading route at full force. A prime example of OP's request.
Photo Hunt
Mom is one of the many many girls in the game. You can chose to be loving or dom. With mom it doesn't go as hard in the dom route as with other girls (yet), but enough to deserve to be included on this list imo.
The Regional Manager
Mom is not introduced from the start, and when she is in the game she is mostly a secondary character. Still, she has several events and all of them fits the bill. Also there are hints that she is going to be a much more important character in the future, at least plot-wise.