GMC, typically, has started around Thanksgiving (US), and once or twice in the beginning of December, IIRC. Hopefully, we will still have it, this year (2020).
As for Daily Dare, I don't think it will happen, per this:
ref: Neopian Times Editorial, Issue: 900, 1st day of Hunting, Y22 (1 May 2020), Question #2 - http://www.neopets.com/ntimes/index.phtml?section=editorial&issue=900
Although they didn't answer the question directly, it gives the impression DD is cancelled/not going to happen. I could be wrong, been wrong before, and would like to be proved wrong by Neopets h