In article , Nick Maclaren
writes
Your broad bean plants will have suffered from the rapid drop in
temperature but they won't be dead. If you have any horticultural fleece
or similar you could give them some protection with it but don't try
doing anything else. They should recover when conditions improve and
begin to put on new growth, but they will probably have had a set-back
resulting in the crop being a little later than it may have been.

Probably, but not necessarily. The worst conditions are alternating
warm, wet ones and hard frosts - those can kill even broad beans.

If you have those weather conditions many plants will have a difficult
time but we have never lost broad beans. Dwarf varieties tend be a
little less affected than taller ones and a little help with frost
protection is a wise precaution at this time of the year.
--
Alan & Joan Gould - North Lincs.