I've managed to make a breakthrough in researching the parents of my x3 Grt Grandfather John Tolley but the information I've found has led me into yet another brickwall

I've found the marriage entry of Johns' parents:
William Tolly & Esther Masus 3rd April 1797 in Ribbesford, Worcestershire
Great I thought I might be able to research Esthers family but her surname is a complete mystery to me. I can find no record of any Masus on the IGI in the Worcestershire area and also no information listed about the meaning of the surname.
Is Masus a surname or has it been spelt incorrectly and if so what the dickens could it be ?
I've searched and search but found nothing and I'm baffled.
Any ideas
Kind regards
Adrian