This is going to sound kind of crazy, but I would be SOOOO much more scared of a granny showing up with a knife in the middle of the night, as opposed to an explosive robber. With the latter, you know what they are after (presumably your stuff), and nobody is going to give you grief if you stood your ground and fought back. Since guns are much more difficult to get in Canada, I would probably arm myself with a bat or a cutlass, and if the guy got in, I would start swinging for the fences.
With granny, I would be second guessing as to whether she is mentally ill and needs help - do I open the door and try to reason with her? Leave her outside as she wonders around to windows and doors with a knife? Or do I employ a no age discrimination policy and look to cave grannies head in?
I am a bit ashamed to admit this, but there would be a small part of me that would wonder if she was possessed or some type of ghost. As a scientist and fairly logical person, I know I shouldn't believe in that stuff, but that video in the OP is creepy as hell.