Rights of a surviving Spouse to deceased husbands inheritance

Son, one of 5 siblings named as beneficiaries in Fathers will, predeceases his parents. One of siblings is the exector of the will. The deceased Son leaves a surviving spouse and children. Question: Is the surviving spouse entitled to know the contents of the will (able to see a copy) and if not specifically excluded in the will is she entitled to what would have been her husbands share of the inheritance? If so what process must be followed to insure that she is dealt with fairly.
My mother recently received small sum from 'three" (not all of them) of the surviving siblings (My Fathers, brother and sisters) with a note saying that they had decided to give her a SMALL portion of "their" inheritance as a thank you for taking care of their father for two years. When she questioned this she was informed that as my Father had pre-deceased his father by a "certain amount of time" that his portion of the inheritance defaulted to the other remaining brothers and sisters. There is something about this that doesn't seem right, this "gift" they have offered her essentially is treating her as a caregiver that is not related to the family and also by this association disowning her and her children, and we are wondering how we can find out the full truth.

There is a will and my Grandfather passed away in the summer of 2007

Thank you for your time, and I look forward to hearing from you

The will could be written so that she gets property or not--it can be done both ways.

If the executor will not discuss with her, then hire counsel and subpoena anything you need if you suspect fraud or improper dealing.

Even the threat of that will likely cause some compromise.