Distribution of father property after his death

Your mother if alive and your siblings have equal rights over the property.  But your grandmother has not right.

What if grandmother died after the death of the my father

Yes! Your grandmother is a 1st class heir. Yourself and you grandmother are entitled for half of the share of your father's property and after your grandmother's death, all her children will get equal share i.e 1/3 in your case. you will again get 1/3 of your grandmother's property as your father predeceased. Irrespective of what your grandmother got from your father, you are also entitled for 1/3 of all your grandmother's property if she died intestate i.e with out a will