The property of a female Hindu dying without a will shall devolve according to the following rules:
(a) firstly, upon the sons and daughters (including the children of any pre- deceased son or daughter) and the husband;
(b) secondly, upon the heirs of the husband;
(c) thirdly, upon the mother and father;
(d) fourthly, upon the heirs of the father; and
(e) lastly, upon the heirs of the mother.
So after the death the whole property of your mother (movable and immovables )equally distributed among you , your sister and Father. Adoption” means the process through which the adopted child is permanently separated from his biological parents and become the legitimate child of his adoptive parents with all the rights, privileges and responsibilities that are attached to the relationship. So you have also right over the property of adoptive mother. Claim all things of deceased mother