Grandmother property issue

Sir, My Grandmother had two daughters, One is my mother and other is my aunty. My grandmother had a 5 acre land property In my village. In the year 2002 she had transferred the total property to my mother. As my aunt is a younger daughter So that my mother had paid the half of the amount to my aunty according to land market price at that time in 2002. My aunty and grand mother both had signed on the land gift deed and registered on my mother name. At that time the total land rate was around 4 lacs they had taken 1,80,000/- and signed for land registration. My aunty and her husband also signed on 20 rs bond paper about for taking the amount of rs 180,000/- amount for trasfering the land to my mother. Now in 2016 the land market price has highly increased And my aunt and her sons had completely reversed and telling that they want half share according to the present market rate. Other wise they are telling that they will go legally in court for half share. And also now they are telling that they will return the total 180000/- with interest from 2002 to till date. My aunty had two sons they are asking for half share on grand mother property other wise they are telling that they will go legally and fight in court for half share. At that time In 2002 both my aunty sons are minors around age 8 and 14. Please suggest me now if they go legally in court is there any risk for me to give them half share.