There are many options for you to change the amount of the payments, request a discharge because of hardship or to act so that the Curt will convert the case to a Chapter 7 or dismiss the case entirely. As your stepson had an attorney to file the plan originally, it would really be best to consult the attorney on his options; but if not, he should consult a local attorney in any event before acting precipitously.
Unless the case was previously converted, they have a right to dismiss the case. However, if there is a deficiency from the foreclosure, that may not be a good option. If they qualified to file Chapter 7 when they originally filed the case (or at least were not prohibited from filing Chapter 7), then they should be able to convert. They might even be able to get a hardship discharge. One issue will be whether the loss of the house and mortgage has led to a decrease in expenses without a decrease in income. This leads to excess income making a conversion a potential abuse of Chapter 7. If they have been in the case for at least 3 years, they may be able to modify the plan to stop the case and get a discharge.
They need to talk to an attorney about the options and which is best given their change in circumstances. If their filing attorney will not respond, they need to consult with another.
[This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]