Your message seems incomplete, but the answer will probably be something like this:
You need to look at the day that your grandfather landed in Canada. Let's say it's November 1, 2015 as an example.
Count 5 years forward from that date. Result; October 31, 2020
Then:
a) In the period from November 1, 2015 till today, count the number of days your grandfather has been in Canada.
b) count the number of days from today till October 31, 2020 (tip, there's a calculator on timeanddate.com)
Add the numbers from a) and b) together.
If that number is less than 730, your grandfather has not met the residency obligation and will likely be reported upon entry into Canada meaning it's almost certain he will lose his status unless he appeals and it's found he has humanitarian and compassionate reasons to have been outside of Canada for so long.
Now let's say your grandfather landed more than 5 years ago. In this case, you need to count the number of days from today going back 5 years. This total must also add up to more than 730.
Forget the validity dates on the PR card. They are completely irrelevant.
To look at it another way, as soon as a PR spends more than 1095 days outside of Canada in any 5 year period they've failed to meet the RO.