As noted above, your parents will need to apply for their MSP coverage as soon as they arrive. Unlike other provinces, BC is particularly slow at issuing new MSP 'care card's. As soon as you arrive, if you apply right away, you'll be expected to wait the full two months plus the remainder of the month you've applied in before coverage comes into effect. But if you don't apply right away, MSP won't count the time in the country before your application towards your waiting time.
In the meantime, your parents SHOULD be covered under an 'emergency medical' visitors to Canada policy. Even though the chances of an accident or illness are small - any medical expenses that do result from a sudden illness or accident can be quite large ( over $4000/day for hospital bed in BC - not taking into account any surgery or medical testing).
You can get an instant online quote for a short term visitors to Canada insurance policy (all top companies in Canada quoted and purchases made online) from BestQuote Travel Insurance Agency:
http://www.bestquotetravelinsurance.ca/visitors-to-canada-insurance
If they currently have any pre-existing medical conditions, their coverage options may be somewhat limited, although if you have questions you can read over the differences between policies here, or call 1-888-888-0510 (or 604-259-2544) with questions:
http://www.bestquotetravelinsurance.ca/visitors-to-canada-insurance-compare-pre-existing-medical-conditions-stable-period