Her name was Mary Crocker.
GUEST, SARAH CROCKER
GRO Reference: 1844 M Quarter in TOTNES Volume 09 Page 593
GUEST, MARY CROCKER
GRO Reference: 1847 D Quarter in TOTNES Volume 09 Page 496
GUEST, HENRY GUEST CROCKER
GRO Reference: 1849 D Quarter in NEWPORT Volume 26 Page 97
Henry's birthplace should be Magor not Major.
She's either Mary Ann Crocker, daughter of John and Sarah:
"England, Devon Bishop's Transcripts, 1558-1887," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:Q2M3-DNKH : 15 March 2018), Mary Ann Crocker, Ugborough, Devon, England; citing Baptism, The Devon Record Office, Exeter.
Or Mary Crocker, daughter of William and Elizabeth:
"England, Devon Bishop's Transcripts, 1558-1887," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:Q2M3-6QWY : 15 March 2018), Mary Crocker, Ugborough, Devon, England; citing Baptism, The Devon Record Office, Exeter