Should i file a case against my in laws

I am from pune,my husband was from patna.there was a dispute between me and him last year.i came to pune with my 4 year old kid.we then mutually decided to move back to pune rather living with our families.we used to talk daily on phone,had a last word with him on 7th april 15 tried calling him on 8th he didnt recieve my calls all day.my sister in law called my aunt and informed he is dead.she didnt tell me.when i called in return she said he died in brain hammorhage.i had no money as i was dependent on my husband,asked in laws to send us some cash or the tickets so we can see him last time.i.e.my child and myself.they said its not possible and send me his pic in the coffin.they said they cremated him the next day in the morning.i didnt go to patna after that.i startd working here in pune again and has got less salary which is difficult for our survival.i am staying at my mothers place since that and only earning member of the family.i am worried about my sons future as well as his present.the last conversation i had with them was in july 15.i asked them to help me with his admission fees and they didnt.i arranged some cash with famliy and friends and got him admitted to a convent school here in pune.school authorities are asking me for his death certificate as he is his father and they never gave saying he didnt had any documents so they didnt get any certificate at the time of cremation.i have no money to hire a lawyer and fight for my rights as well as my sons rights.please advice what can be done.should i register my case with womens commission?or should i hire a lawyer here?do we have any rights in his property?and my son got his rights in his fore fathers property?i dont have any papers of their property.please advice.thanks!