when your parents were alive, they were entitled to transfer their shares to any person of their choice
however on their demise intestate, their shares would devolve on their legal heirs
so on demise of your father, his shares would go to his legal heirs who are his widow and children (i assume his mother predeceased him)
when the widow dies subsequently, her 1/3rd share will go to her legal heirs as per s.15 of Hindu Succession Act - who are widower and children
so the two children (you and your brother) each had 1/3rd share in the shares on demise of your father
later when your mom passed away, her 1/3rd devolved on her sons
therefore you and your brother now have each 50% share in the company shares
thus the shares could not have been transferred to your brother without your specific consent/NOC and in absence of a succession certificate
you need to challenge that transfer by filing a suit/ NCLT case against the legal heirs of your deceased brother and the company
also you will have to prove your father's Will in order to claim absolute rights over the company shares
if the shares held by your aunties were transferred in their lifetimes then it is fine. However after their demise, such shares cannot be transferred without a valid succession certificate obtained from court