Asper Indian Succession act S. 33, S. 33-A, S. 34 of the Act govern succession to the widow. Together they lay down that if the deceased has left behind both a widow and lineal descendants, she will get one-third share in his estate while the remaining two-thirds will go to the latter. If no lineal descendants have been left but other kindred are alive, one-half of the estate passes to the widow and the rest to the kindred. And if no kindred are left either, the whole of the estate shall belong to his widow.
if he has left no lineal descendant, but has left persons who are of kindred to him, one-half of his property shall belong to his widow, and the other half shall go to those who are kindred to him, in the order and according to the rules hereinafter contained; (c) if he has left none who are of kindred to him, the whole of his property shall belong to his widow.
If your father dies without a will or any arrangement, the above process shall be followed.
Being a step mother and also a widow the same rule applies upon her intestate death too.