If a 2nd wife dies before her husband and no new will was not made, who gets her 50 percent under the will?

A well drafted Will usually answers the question you have posed.  Most Wills state that if so and so predeceases me then their portion goes to x or their heirs or whomever.  That being said, if the Will does not so provide then I would suggest that you seek legal help in your area as to local law on the subject.  Here is why.

It is difficult in this forum to lay out all the facts necessary to give you a reasonable response.  For example, what real property are we talking about?  Was it jointly owned?  Were there survivorship rights or not?  Were there annuities involved?  Was the personal property spelled out and/or who was to determine who got what?  It is possible and likely that the Court will interpret that portion that is not clear in accordance with State law. 

It is obvious that the sons who got $1 are not happy with being cut out, so to speak. In all states, except Louisiana, children can be disinherited.  And some Will's have a provision that states they lose the amount given if they challenge the Will.  It is also obvious that the heirs of the second wife want what they believe is theirs.  Having the Will interpreted by a legal expert in the area who can give you a reasonable answer based upon the reading of the Will, assets held and state law may save you legal bills in the future in challenging the Will.  Maybe a settlement can be reached without eating up the inheritance in Court.  Good luck.