Greetings: HOLD OFF ON YOUR TRIP TO KESWICK... When I mentioned to my associate Bill Britnell that I was interested in responding to your querry and I asked him to check for the burial of George and Rena ... his first and immediate response was Oh, Aunt Rennie ... you won't find a tombstone for here there and proceed to tell me the story. Following the death of George Thompson (date and place unknonw)Rhena Thompson married Samuel Chapman on 3 September 1854, at which time they both stated they resided in North Gwillimbury. Samuel Chapman was a brother of Bill's ancestor, Ira Chapman.
Apparently Samuel and Rena moved to Oro township, and he died there in either 1870, or early 1871 as he is listed in the 1871 census death schedule, and she is listed as a stray, obviously living with some of her Thompson children. So, to find her death record you will now be searching for a Rena (Rennie, Rhena, etc.) CHAPMAN perhaps in Simcoe County - after 1871!!
Bill has quite a bit more on this family, so if you e-mail me privately I will supply you with his mailing address. He is not automated in any way.
Hope that this helps! Cheers J. Brian Gilchrist
Hope that this helps