Close....
Close, eh? Hmmm. Well, at the risk of embarrassing myself, I'll work through this.
Scrimmage play.
The ball carrier (and receiver of the snap) fumbles the ball from behind the NZ at the b-30 (the B-30 is end of that run).
The ball is still in Team A's team possession.
The ball travels to the A-45 (still behind the neutral zone, and still loose from the fumble).
The ball is muffed (irrelevant by whom, and a muff changes nothing).
The ball continues to travel to the B-48 (two yards beyond the NZ, which means almost nothing in this case).
At the B-48, A66 kicks the ball. Since there is no mention of A66 gaining player possession, we can assume the ball was still loose when A66 kicked it. A66's kick of the ball is a foul for illegally kicking the ball (10-yard penalty and loss of down, with Basic Spot enforcement). However the illegal kicking foul did not change the status of the ball - it is still loose from the fumble.
The ball, still alive, travels out of bounds at the A-35 (15 yards behind the NZ).
The ball becomes dead.
Since the spot where the ball went OB was in advance of the end of spot of the fumble, the ball is returned to the artificial dead-ball spot - the spot of the fumble.
Since the ball is dead behind the line-to-gain, and the previous down was fourth down, the result of the play is Team B's ball at the artificial dead-ball spot. The next play would be B, 1/10, A-30, PC=25, GC=snap.
Team B also has the option to accept the penalty for the Illegally Kicking the Ball. The distance penalty is 10 yards. The loss of down applies, so Team B will be awarded the ball, if they accept the penalty. The penalty is enforced according to Basic Spot enforcement rules. The ball was loose from a fumble from behind the NZ, so the Basic Spot is the Previous Spot. The foul occurred beyond the Basic Spot, so the penalty is enforced from the Basic Spot. Thus, the penalty would yield B, 1/10, A-40, PC=25, GC=Snap.
The result of the play is more advantageous for Team B than accepting the penalty. So, Team B will decline the penalty and accept the result of the play.
B, 1/10, A-30, PC=25, GC=Snap.
Ah, that's closer.
Robert