It means grandma has an opinion but not a filter. You should tell grandma you love her, spend time with her, and live your life how you want.
Discussion
Exactly this.
My hair has been short and dyed, long and not, and short and natural. Two of the three my Grandmother told me I shouldn't have my hair like that.
Your proposed response was what I've done the last five years.
Anyone who isn't my grandma: they can go pound sand.