Under $100 Bed and Breakfast and/or Hotel in Montreal for one night July 16, 2019

You will have to be exceedingly lucky to find a B&B for $100 a night, in Montreal in the middle of the busy tourist season, for a date 4 days from today. Best of British luck just the same.

Look at booking.com, hotels.com, airbnb, etc. Not sure you'll find what you're looking for but good luck to you.

Have you tried the University Residences. I believe McGill University rents out rooms in the summer months

Thanks for mentioning that Lisa, I'd forgotten about that. I actually stayed at McGill residence hall when I stayed in Montreal many years ago. No frills, basic but very nice, and good location.

I saw this through hostel world but Concordia Un has private rooms for $44
https://www.hostelworld.com/hosteldetails.php/The-Grey-Nuns-Residence-by-Concordia-University/Montreal/273133?dateFrom=2019-07-16&dateTo=2019-07-17&number_of_guests=1

Well, that’s interesting, Maria! I knew that the huge Grey Nuns property, taking up a city block in downtown Montreal, has been transferred to Concordia University but wondered what Concordia would do with it. I expect the rooms will be small with WC down the hall ..... the Sisters would expect nothing more.....but the price is right. I stayed in a students’ residence in Glasgow once and I don’t ever need to do that again.

Please recommend where to stay for under $100.

Canadian or US dollars?