You might have a case for the donation (as an XP-earning activity) being an overall extending activity, but that case isn't going to result in mile extension by the end of the month.

XP from the credit card might or might not: it's less ambiguous that the miles from the card would, but those miles won't post until next month which is too late.

With this short period to act, the best course is to find the cheapest mileage-earning flight before the end of the month on SkyTeam and fly said flight, crediting it to Flying Blue.

Had you noticed the expiration even a month ago this would be somewhat more straightforward and likely cheaper, but waiting this long is what it is. That said, if you weren't regularly logging in to your FB account and seeing the looming expiration, it might be a stretch to expect to get much value out of those miles.