There is no globally correct answer - and I certainly don’t want to send you into an emotional tailspin, because of one lesser grade someplace.
A college is not likely to rescind for “normal” variations - they realize that things “do happen”.
The stakes rise and fall somewhat with how elite the college is, and how much a “stretch” vs. “fit” your particular numbers were for that particular college. But as long as you can honstely say you are continuing to do your best and get whatever fair grades resulting from that consistent effort, I wouldn’t worry.
But, if you are trying to find out how much you can “safely” slack before it has consequences, then you’re asking for gambling advice which no one will be able to give, down to the decimal point.
Basically, if there was a personal tragedy, or other important life event, and it impacted your academic ability - then the college will seek a reasonable explanation to understand that there was a justifiable reason. You’re an adult; “senioritis” is “not a thing”, it’s just an excuse less mature peers made up - thus would not be acceptable among adults.