Finally, a break and the solving of one mystery, but not all.
The Dennison name is misspelled as Davison in the 1901 census transcription. This is where Charles Vantassel is listed as a Lodger. I did not realize it was with my grandfather’s family!
So, while it is still a mystery as to when Charles Dennison died, and it is still a mystery as to who is the father of Alma/Alva/Alvira Dennison and Gladys and possibly Bernard as well, we do now know that Charles Vantassel was living in the home in 1901, three years prior to marrying Alice Dennison.
This is the 1891 Census for Charles Dennison:
Here is the link to the jpeg of the actual census record, rather than the transcription. Will try from now on to look at the actual rather than a transcription. And if that doesn’t work I’ll back up a page and put that link. They both worked for me.