See firstly the property has will be divided in 4 shares in sons and mother.
Now the mother since she is no more her share will be divided upon the sons and daughters (including the children of any pre-deceased son or daughter) and the husband(is no more in your case.);
So on demised sons children and alive daughters.
Further the Share of individual sons will go onto there wife and children and will be equally divided.
So firstly in 4 parts and then will be further divided as mentioned above.