The only credible information I know of about the history of the Vaus or de Vaux family at the time of the Norman conquest of 1066 is from the book “The Anglo-Norman Era in Scottish History” by G.W.S. Barrow which suggests that the family was not of great distinction at this time.
Playfair in “Baronetage of Scotland, (quoted by Balbirnie) and Balbirnie in his “Genealogical and historical account of the family of Vance” claim a connection with the lords of Baux, in Provence. To my knowledge there is no documentary evidence to show any such link or any reason to suppose that there is any truth in the idea. I believe that the heraldic evidence shows clearly that there is no such connection.
I have found that Vans, Vanns, Vanse, Vas, Vass, Vaus, Vauss, Vause, Waus, Wauss and Vance all seem to be completely interchangeable even within a single document without any discernible pattern of use according to the date or particular branch of the family.
~Jamie Vans of Barnbarroch