As this is her visa on the line. It will be all on how much risk she wants to take. If she is not comfortable with that risk that is up to her. Do not keep pushing her to try, it's not your visa that will be cancelled.
I would never tell anyone to take that risk just because you think it is a legit reason to visit. Many many ppl get turned around for legit reasons.
She does have ties to home, like her husband and kids, but at the same time those ties have not stopped her from coming to the US twice already without them.