Not necessarily? The stomach is usually empty withing an hour, depending of whether you have a three course meal or just a light snack. The others obviously didn't have anything to eat. Therefore by deduction she must have been the last to die?
Now if she was so ready to defend her twins to the death, you would think that if she was murdered she would have been among the first to die. But there is every indication that she was wandering around the house getting a snack from the kitchen early in the morning. One can't help wondering why she felt like a snack. Was she restless in the night? Or could not sleeo perhaps? Why was that I wonder?
The stomach empties after about 3-4 hours. The report doesn't say whether or not there was anything in the stomachs of the others, but I'm prepared to accept that they probably would have recorded it if there was. I don't see why that fact that she may have had a late night snack means she must have dies last, but I think she probably was the last anyway. I doubt she got the chance to defend the boys, I think they were probably dead before anyone else realised what was going on.