Inheritance

The posting is confused and lacks clarity. Please post simple facts.

Consult a local prudent lawyer with relevant documents for proper analyses, professional guidance and necessary proceeding as you are unable to convey true / simple facts of the dispute.

Are you trying to provide clarity or confusion? Please clarify the following aspects if you really have a problem and desire to have a meaningful suggestion:

A. "My Father is living in a home since his marriage which belongs to his mother who is alive."

Admittedly, the property belongs to his mother or your grandmother. She is the absolute owner. She can deal with the property in any manner she likes, during her lifetime. May be your father and mother have been staying in this property. But that does not vest your father any right or interest in this property and hence cannot make a Will of this property. If at all made, it will be just a useless piece of paper.

B. "But his mother inherited the property upon his grandmother death"

His grandmother - do you mean to say your father's grandmother i.e. grandmother's mother? If so, how - by partition, settlement/gift or  Will?

C. "He, his mother and 5 siblings have a share in his father's property who expired in year 93"

""Would she be able to claim a share in the property of her late father in law."

Is this a different property? Who is in possession/occupation?

D. "What legal options does my mother have so that after the death of my father they should not throw her out of her marriage home. Also since my father named her as the beneficiary in his will"

Which are the properties covered by the Will? Why you have the feeling that "they should throw her out of her marriage home"?   Who are "they"?