Winning with a blunder, or how you see this Stockfish reaction?

Dear more experienced players,

on Stockfish level 4, computer stopped to what it read to be a blunder, and finally ran out of time. Do you think it absolutely was a blunder, or
a)
13... axb4
14. axb4 Bxb4 (?)
15. Bf7+ Rf7
16. Rxf7

b)
13....Bb6
14. bxa5 Bxa5/Bc7
15. a4



Any experienced insight welcome, have a good day.

16. Rxa7 (of course)

stockfish time out ??? you hacked

without looking into too much detail' I see Bxf7+ & Bxc3 as well as Rxa7 so if I'm Playing Blaclk I might get very happy with two Pieces for a Rook ( The Knight goes away Bxc3 later @HardLearningGuy

Thank you for comments,

especially NM ThunderClap.

Stockfish sudden stopping and interpretation were surprises, and I needed "2nd opinion":
Thanks.

B4?? axb4 axb4 Bxb4!! Bxf7!? Rxf7

...and Rxa7?

@HardLearningGuy said in #7:
> ...and Rxa7?
then Bxc3