grace period with TN visa

what is the grace period on TN visa after the visa expires to make any status change or move back to Canada.

Generally it is acepted that a reasonable amount of time is 10 days from the day that it expires, or your employment terminates before it expires.

Technically there isn't one, I looked it up after someone asked before. You have to leave by the expiry date of your I-94 if you're still in employment. If you get laid off or something like that, there was a court case back in the 90s as I recall and the result of that was that you have a "reasonable" amount of time to leave and CBP seem to think that means 10 days going by their field manual.