I have a suspicion that Martha WILLIAMS is in fact Martha WALFORD.
1841, 1861 and 1871 Census entries for Martha and family may help as may this death registration:

Deaths Mar 1878
WALFORD Martha 67 Westbury S. 6a 168

This is the entry from the Burial Register:
Martha WALFORD

Entry Number: 564
Year: 1878
Month: Feb
Day: 13
Surname: WALFORD
Forenames: Martha
Place of Residence: The Lime Kilns, Lydbrook
Age at Death: 67 years
Officiating Minister: H. T. Hoitt, Vicar
Cause of Death:
Memoranda:
Transcriber's Notes:
Register Reference: P208 IN 1/11
Page Number: 71
Church/Chapel: Lydbrook

Mike