I am sorry for your loss. You need to speak to your IP. Hopefully he or she can propose a variation to creditors that the IVAs be concluded on payments made to date.
In theory ( you actually have two IVA's, one for each of you, if both yours and your husbands debts were included) your IVA would continue and your husbands would end and his outstanding debts become part of his estate --- but, as I say, the creditors may agree to close the arrangement (s) and still write off the debt.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk