a man wants to adopt of 30 years old married girl , as he had no daughters

Adoption can be done/ registered for a minor  before the child attains the age of 14 years but not 30 years old woman.

Adoption can be done  only minor  not  30 years.  What is the age of A man ? 

Adoption in islam is prohibited and I think you belongs to muslim.Apart from this a hindu can adopt a child who is not more than 14 years so drop the idea it would be illegal.

Only a child can be adopted and not an adult.  

Section 10 (iv) of Hindu Adoptions and Maintenance Act 1956 : "Persons who may be adopted"

No person shall be capable of being taken in adoption unless the following conditions are fulfilled, namely : -

(iv) he or she has not completed the age of fifteen years, unless there is a custom or usage applicable to the parties which permits persons who have completed the age of fifteen years being taken in adoption.