What document options can be executed to transfer property rights in absence of will

My father passed away recently without making a will. We are a family of 2 sisters, myself and my mom. And have 2 properties at our disposal. One is registered in thane area and all documentation completed with registrar office for sale while buying from the 1st buyer but so far the society has not issued any share certificate to any member of the society and no clarity provided for the same.this property was purchased jointly by my parents in which 1st name was of my father. Now what documents need to ve executed to make my mother as sole owner of it. Second property is also in thane purchased some 45 years back by my father via a normal sale deed but it was not registered with registrar office. Subsequently society was formed and share certificate isued in my father's name and we also pay property tax to municipal corporation and it stands in my father's name. Would like to know what documents need to be executed to make my mom sole owner of it. Your valuable guidance would be highly appreciated. Thanks in advance.