A lot of this depends on the Consulate, you mention ESTA so I doubt you have too much to worry about.
I think my letter was one sentence. None was interested in looking at more that a photo of both of us.
You are focussing on the wrong issue
Certainly from the UK there are plenty of options for companies that will handle the move with insurance as an add on.
ESTA is good for 2 years.
VWP is 90 days and automatic disqualification if you overstay, apart from anything else you need a return ticket or onward travel within those 90 days so I assume the return flight was rearranged.
I agree there is no way you could not know.
It was very silly to overstay the VWP, so the question is with all these issues will she ever get a visitor visa.
The only think I can think of is time, give it a few years and try again?
It can be difficult for someone from a VWP Country to get a B.
In this case someone who abused the VWP privilege is going to find it very difficult to get a B.
Less than 10 K3's are issued per year btw
I doubt anything changed since her prior refusal and she is accumulating a bad US record.