Open Question: Monthly "Income" from sale of business (no job): How to get a mortgage?

Hello. This is a question for my mom. My mother owned a company and sold it. She collects roughly $15,000 - $20,000 per month from the company as payment from the sale. She is older so she no longer works a job. She also owns several hundred thousand dollars of assets (cars, boat, real estate). She will be collecting checks from the business for about 5 more years. She wants to purchase a house in British Columbia and move there. As of right now, the banks will not grant her a mortgage based on this situation and she will be forced to pay the house in full meaning she will have to settle for a cheaper house. She would really like a nicer more expensive house but this would only be possible with a mortgage. Is there anything she can do so the banks will give her a mortgage? Thanks you very much for any input!