I found Frank's obit and it confirms that he is buried at St. John's Norway I have the transcript for that Cemetery so I looked them up thinking Kathleen might be buried with them but no luck I found them on the transcript so they must have a gravestone. Sometimes family members are buried close to each other so I checked the transcript but can't see her name on there that doesn't mean she's not there she is just not on the transcript.
Since we don't know what surname she was using you might want to contact St. John's Norway and see who made the arrangements for Frank's funeral, another that might help find her surname is doing a reverse lookup for 48 Rose Avenue to see what name is shown there if she was living with her Husband his name might come up under that address. If you contact the Toronto Reference Library they will do that for you. I would do it but I won't be able to get to the library for a while.