The surviving spouse does not need to do anything, now that she too is dead.  What about the beneficiary of the surviving spouse?  If the irrevocable trust was done correctly, it is not included in the estate of the second spouse to die.  However, those arrangements were often used many years ago to avoid estate taxes, when the exclusion was much lower.  There hasn't been much need for them lately.  At least, for federal estate tax avoidance.  So it makes you wonder who was keeping an eye on the situation, and whether they did it correctly in the first place.