As stated above, I was in this situation 7 years ago when my shooting partner passed away... I was able to advise what she needed to do and attended the Firearms department with her. The bullets /ammunition were transferred to me along with one shotgun and one FAC air rifle. The rest continued to be stored in his gun safe. I then posted the various firearms on a number of forums for sale and arranged and attended the transfer of sale for these.Are we to assume that your friend's widow did not apply for a temporary permit?
Purely out of curiosity you mention a .44-40 martini action American rifle, do you have any more details as to what it is.
Alternatively an RFD may chose to sell them for 10% commission..