It is always tricky to move or transfer Domain out. More so if the domain whois records does not reflect the registrant detail but third party. I would advise you to tell A to ask B to change all Domain whois record to A's email first, so that A can then request the Registrar to send the password to the admin email, without leting B kow the true intention of moving the domain out from him.
Cos, you should also check if you are working with the same registrar, if yes, then it is usually a reseller transfer which usually do not need password. If it is difference registrar, then password is needed.
Cos, you should also check if you are working with the same registrar, if yes, then it is usually a reseller transfer which usually do not need password. If it is difference registrar, then password is needed.
