There seems to be conflicting opinions as to whether the ancestral home is in https://fr.wikipedia.org/wiki/Sainte-Foy-de-Montgommery or https://fr.wikipedia.org/wiki/Saint-Germain-de-Montgommery (this may have something to do with the fact they are right next to each other).
Either way it is definitely not "Mount Gomeric,Normandy,France" as there is no such place.
The legend is that the family name, Montgommery, is a contraction of "Mons Gomeric" a mountain or hill-top stronghold once the possession of a progenitor named Gommeric(sp). Who this Gommer is varies from a Norman to a Frank to a Roman depending on which legend you subscribe to. Currently on Geni we show the ancestor as a Norman named Gorm / Gommer
Hugues De Montgomery is a duplicate of Guilliaume's son, Hugues de Montgomery, but with different parents.