Maybe someone already brought this up, but...
Mid-fifties is not young when you emigrate to a foreign, first-world country. It does not help being in Canada if you are not plugged into the economy. In mid-nineties, my country saw a lot of emigration, to US and Canada. My generation did well, but the parents did not. Getting a job was difficult, there was employment discrimination, being over forty, not having experience or credit history, speaking with an accent and all. There is culture shock that needs to be absorbed before they will even be valuable as employees at the western level. That gets exponentially more difficult with age. If they try hard, they will probably land a minimum-wage job. Will your father accept that, after running his own business and apparently doing really well? Some people, especially those supported by others, are 'above' or 'too proud' to work menial jobs, after having college degrees, expensive lifestyles and whatnot. When your father was making all that money, did they hire other people to clean their $800,000 house? Drive them around? Did they cook for themselves, or did they eat out a lot? Will they be grateful to you for the 'opportunity' to work as cleaners, drivers, cooks...? When they expressed a desire to come to Canada, they likely did not have hard, underpaid, disrespected work in mind. They were probably expecting to restore the prosperity they once experienced in the home country. My guess is that they will be very unhappy in the best realistic scenario, and likely resenting you for 'misleading' them.
I think you are expecting too much from your parents. I wish you good luck.
On a different topic, a house is only worth what people are willing to pay at that moment. There is no such thing as a house being worth $800K, but selling for $600K (if it's been on the open market). Given the economy, your parent's house is probably worth much, much less than the $600+ they were offered last year.