You have posted that "My grand mother has to (two) properties. "
It is felt that it is self earned/self acquired property of your grandmother.
Which personal applies in this case e.g. ; Hindu Succession Act?
Is your grandmother alive?
If NO; Your grandmother died in which year?
If she is Hindu and her property is self acquired/absoloute to her then, :
She can gift it to anyone in her life time and gift (if not conditional) shall confer ownership on donee with immediate effect.
She can give it by a valid WILL to anyone in her life time, andit shall confer ownership on beneficiaries after her death.
Te gift and deed and WILL can be contetsed on valid grounds and shall be subject to test of law.