ShlomiLevy – first of all my sympathy for the sad loss to your Grandmother and your family. Clearly this is a very sad time for all of you.
However, I suspect that you are being unfairly harsh on Norwegian in your comments and that most airlines would respond with sympathy but little more in the circumstances you face. This is a risk we all take with non-refundable tickets. The answer, of course (and it is easy to be wise after the event), lies in travel insurance which would certainly have covered your outlay for your grandparents’ tickets.