Urgent: Can I transfer my H-1B?

I had been working for company A more than 5 years;
Now I am transferring H1B to company B which was filed a month ago.

I have an offer from company C, which is better then B.

Is there any problem transfer A' H1B to C?

USCIS has recently released a Public Notice saying that
USCIS now requires demonstrate that you actually did perform meaningful work for that original employer.

In my case is original employer A or B?

What if my transfer to B get approved before I file a transfer to C?
Will the transfer to C be denied because I work for B only 1 month or two?

Thanks so much for any input