TheFork users who ate in Mons have said really good things about L'Effet Boeuf, Maxens and Phénicie. Maybe you should give them a try!
Some of the more popular Good for families restaurants where you can go with your family in Mons according to TheFork users include:
L'Effet Boeuf, with a 8.8 rating
Maxens, with a 9.5 rating
Phénicie, with a 8.9 rating