Currently the house property is in joint names of Wife's of A & B respectively, if A is your mother then she can gift her share in your favour through a Gift Deed. However Wife B will be your father brothers wife, your aunty, therefore she cannot gift her share in your favour.
she will have to gift the property to her husband, he inturn will have to gift it to his brother, your father and in turn your father will have to gift it to you.
Your best option would be to register a family partition deed amongst both wife's of A & B, in your favour, this must be registered in order to effectively get the Katha to the property transferred into your name. Partition Deed amongst family members is less expensive as it is amongst family members only.