Adopeted by grandma after her husband passed

How did your grandma adopt your father? Your query requires clarity.

In the Will she mentioned i am growing this child from chidhoold along with my husband  and they did all the rutival to my husband like this in the will she mentioned and registerd and give proper to all the property of her / and husband .

Vague and confusing facts.

Yes,  the query reveals confused and vague facts.

Is the so called grandma is alive?

What do you mean by "my grandma given registered will / Power of atony to all the property of her/ her husband to father at 1980"?

Who is this relative claiming as a legal heir? How is he related to the grandpa?

In the absence of a proper adoption deed, the adoption cannot be recognised as legally valid.

Second thing, if the grandma was the only legal heir to the grandfather, then she will be entitled to inherit/succeed the properties left behind by her late husband.

Even in that case the grandmother should have legally adopted your father provided your father was minor by age at the time of adoption because adoption can be done only to adopt the children and not an adult as per law.

If the Will has not come into force then there is no reason to recognise the adoption  besides the power of attorney deed will not confer title to your father. 

If somebody is challenging the Will or claiming any share in the property as a right then you fight it out on merits on your side.