Agreed with
canuck78. Private health insurance would take care of the emergency medical costs in case you suddenly get sick or injured and, thus, need immediate medical attention (including a doctor's or ER visit, hospitalization, x-rays and tests, prescription drugs, etc. ). Any elective, routine or otherwise "non-emergency" procedures are not covered by such insurance.
Depending on the type of visa your parents have they would have a few options when it comes to medical coverage. If they apply for a Super Visa (at least for the first time), then they would be required to get insurance from a Canadian insurance company for 1 year with at least $100,000 coverage per person.
On the other hand, with a regular Visitor's visa, although they are not required to purchase insurance, it is still recommended to do so since they are responsible for any medical costs they may incur while visiting Canada. It is generally recommended to go with a Canadian option given the fact it is easier to get your bills paid for and within a shorter amount of time compared to a travel insurance from their home country.
If you are looking for possible options, you can check out and get an instant quote for most of the Canadian insurance options using the following link -
Medical Insurance for Visitors to Canada.