Many times there is a ceremony of sorts where friends and family meet and perhaps share stories of the deceased. There is usually food and drinks after and many view this as closure.
This may take place right after the death or several months later.
I would send a thinking of you/sympathy card and a charitible contribution in his name to the American Cancer Society.
As always be there to listen and console her.
Thinking of you Patti and I am sorry for the loss of your brother in law
What we do in life echoes in eternity.