Hi Colleen,
I was at Rebecca's grave a few weeks ago. She died in 1863 (exact date hard to read). See photo of her headstone attached. Three of her children are buried with her, according to the headstone.
The newly erected sign calls this an Anglican Cemetery but the Roes buried there were Methodists, as per baptism records (and other evidence):
Methodist Baptisms, Montague Township
Children of Thomas and Rebecca:
• Richard F, born 25/02/1854
• Eliza Jane, 04/01/1855
• Richard, born 28/01/1857
• Mary Hester, 22/02/1860
Child of Thomas and Maria:
• John Dunbar, born 03/01/1865
http://www.afhs.ab.ca/data/ontario/baptisms/montaguebapt.pdf