TB, Safety, or???

[Base]

Yes, I forgot to mention it.
So: NCAA rules, Team A´s 3rd&goal on B´s 10. Team A fumbles at 2 and loose ball is kicked form the EZ over the goal line by Team B.
What is the ruling?
-3th down on B´s 1 for A if accepted (rule 5-2-9)
-TB if declined (rules 8-6-1-a and 8-7-2-b-1-exc)
?
And what would the ruling be, if this happens on fourth down? I mentioned AR 8-7-2-IX-b, but as the penalty would half the distance to the goal, Team A would still be short of gaining first down, so Team B´s ball at their own one-yard line?
Please do not try to compare it with Fed (or other) rules, as I know nothing about them
Thank you for answer