my wife father past away 3 yrs before my wife past away but in laws told children they are not entitled to anything since my wife past away

It sounds like your wife's father passed away but his assets were not distributed until after your wife died and were distributed only among his living children.  If this is the case, your wife's estate may have a claim against her father's estate.  If you are the executor of your wife's estate, you can file this claim on behalf of her estate in the probate court where her dad's Will was probated.   It also may be the case that his assets were in trust and the terms of the trust apply to how they are distributed.  If an attorney was involved with your father-in-law's estate, you may be able to get some information from her or him.  Otherwise, you can contact the probate court and ask about fiing a claim against the estate or challenging how it was distributed.  Good luck.