Is her nest in a low spot? This may sound over the top but can you make some sandbags to keep water away? In the end, you may need to grab her and the eggs and put the latter in an incubator (do you have a backup electric supply)?
I don't, by the way, assume the sky is always falling. But in my life, I have seen things go from bad to worse, and I can remain more calm if I have thought through the next steps.
As I wrote earlier, we have lost electricity in the previous two storms of any consequence, so when I consider doing something I ask myself, "how will I do with without electricity from the grid?"
It gets a little primitive here, but so far we have been able to cover basic needs when the lights go out.
Meanwhile, I realized this morning I need more kitty litter. sheesh.