Hussard de Westermann were famous for their victories in Vendée against the catholic and royal Army, and infamous for mass murder of the vendean civilians. Unfortunately there is no OOB to check the regiments of Westermann's brigade.

Looking further, I discovered another site on revolutionary armies.
It is well searched and beautiful, but has some bugs when browsing: better use IE than Mozilla and/or change regiment number manually in url.

According to it, numbering of hussar regiments changed in spring 1793, when 4th regiment de Saxe (german mercenaries) deserted to Army of Condé.

7th / 6th hussars had two squadrons in Vendée 1796-97 then at Moselle Army 1797
8th / 7h hussars had two squadrons in Vendée 1793-94 then at Armée du Nord 1794, Rhin et Moselle 1794-95
9th (former Eclaireur de FabreFond) / 8th hussars fought in Vendée and was at Armée du Rhin by december 1793
Hussars of death company was merged into 14th chasseurs who fought in Vendée from 1792 to 1796. The company kept their black hussar uniform.

Checking Digby's databook, 8th Hussars was involved in actions against Dutch by january 1795 Heusden and Geertruidenberg).

So most probably the 8th hussars.