Going on the assumption that Mary stayed in Somerset and didnt go with George.Found this possible in 1851 Union House Preston Road,Yeovil,Somerset.H0107 Piece 1930 Folio 470 Page 41.
Mary Hebditch,Mother,Unm,30 or 36?,South Petherton.
Mary Ann Hebditch,Dau,4,South Petherton.
Rebecca Hebditch,Dau,2m,South Petherton.
There are a lot of people also at this address so assume its the Workhouse.
Best Wishes Welsh Lady