In whose name will succesion certificate be issued

Recently my husband expired and he has left his mother, me and my four year old daughter, after 2 days of his death, my sister in law and brother in law started forcing me to take care of her which i am currently doing, they wrote a letter to the company where my husband was working on behalf of my mother in law that she is old and that she needs some help so that she can sustain herself, moreover he is not returning the company assets which was given by the company to my husband, now the company has demanded the succession certificate and every day they are harassing me constantly that whatever my husband will get will be divided into three parts. I want to know in whose name will the succession certificate will be issued and what will be the share, my mother in law is old, 70 years of age. I have a four year old daughter. I am a housewife. Moreover my husband does not have any property and all they are claiming for whatever death benefits my husband will get from the company and his savings.