This information is for the province of Ontario, where Oshawa is located. According to this, your friend needs to know the *date of death* to apply for a death certificate. https://www.orgforms.gov.on.ca/eForms/start.do
What information do I need to provide on the Online Death Certificate Application?
You must provide:
First and last name of the deceased subject
Date of death
City or town of death
Parental information about the deceased subject
If applicable, information about his or her spouse or partner.
Who is entitled to apply for a death certificate?
There are no restrictions on who may apply for a death certificate.
There should be an obituary online for those recent dates. If you post his name, someone should be able to find it.
The other possibility is that he is living in a nursing home. How do you know the daughter is the only one listed as living in the house?