My grandmother just passed away and my father is in charge of her estate. Do you know what the inheritance tax amount is for the State of California. We estimate her estate to be worth 2.5million and there is 4 children that this need to be split. There is two properties that need to be sold first. Please advise.

No inheritance tax, and also no estate tax, in CA.

Your father will have to file a federal estate tax form, however. He should go slow here - don't even think about distributing any of the assets to the heirs until he has worked through the tax issues. For an estate of this magnitude he would benefit greatly from the advice of a lawyer who specializes in estates.