4.43.4
 

Am I mistaken or is part (c) usually called a jump ball?

Not saying that is correct, but seems that is always called a jump. And indeed would be a jump ball if A1 returned to the floor while B1 also had a hand on the ball.

Now, I understand that if B1 just touched it while it was still in the hand of A1and B1 was not touching it when A1 returned to the ground - that a travel would be correct.

If B's touch prevented A from releasing the ball, then it's a held ball. If B merely touched the ball but didn't prevent the release, then it's a travel. That's the situation in the case.