Hello Esther I believe but cannot prove that the name you are researching was originally deFoye, or Foye, in France, and derived from the name of the Saint known as Sainte-Foy. From what little research I have been able to do, I believe it is likely that they were Huguenots who arrived in the Spanish Netherlands at the time of the Protestant expulsions, up to and including the Revocation of the Edict of Nantes in the mid-1600's. I have not found the name there prior to the Reformation, and as far as I know it has no clearly Netherlands origin. The name deFoye is ancient in France, and as Foy and Fey it is still found, primarily in the northwest (though it is not the same as the Fey/Fay name derived from Beech). The particle "de" went out of use for the most part by about the 1870's, and the "e" on the end had been dropped long before that.
My family emmigrated from Staudernheim an der Nahe, in the Rhineland Pfalz, to Philadelphia in 1741, and had been at Staudernheim since at least the 1650s. They were members of the Reformed Church during their lives, and always wrote their own name Feÿ which is the Sutterlein form of Feij. Since there is a German name Fie/Fei that is pronounced the same I had long assumed they were German, but the fact that they were actually named Feij, the fact that they were not Lutheran, that they were not farmers, and the proximity of Staudernheim to France suggests strongly to me that they may have arrived there as Huguenot refugees.
Interestingly, one of the earliest settlers around what is now Memphis, Tennessee was a man who had come to New Orleans from the Spanish Netherlands about 1750-52. He is remembered in Memphis as Judge Ben Foy, but in fact he alway spelled his own name Fooy, and clearly it was originally Fuij.