Yes, all Mesnards are originally from France.

Menart is a Franc name. Oliver Menart was a crusader (hospitalier). The name is of German root meaning hard strong. I guess they were pretty tough. These Francs settled in the West of France.

Most Mesnards in this country pronounce the s either as an s which Americanized or as a z. This is a rare pronounciation of Mesnard in old French. They used an outdated letter a large s. Messnard is another translation of this name. You need to bare all this in mind when you look.

Your name is pronounced in a French mannor for Mesnard. I can tell you not to look for Mesnards unless you are Catholic. If so they originated in the Three Rivers region of Canada. If protestant you should be looking for Maynards or Menards. There were Maynards in CT before the War of 1812. Maynard is pronounced the same as Mesnard.
Mesnard is more correct. For my name Messnard is more correct for the pronounciation of my name.

I would take the trial offer for the on line census on ancestry.com. You can do sir name searches for the census.