You knew her husband very well, it is likely that she will know who you are and if not just explain that you are a good friend and ask her if there is anything she needs.
No doubt she will have family and friends who will rally around and help her also, and her mortgage will also have life insurance attached to it.
As for other bills, I would expect any company would give a significant amount of leeway under the circumstances, and I suspect his employer will have everything in hand regarding his life insurance.
My advice is simply pay your respects, ask if there is anything you can do and does she have enough money etc......and then just keep aware of the situation through a mutual friend and then, if it is clear she is struggling then just give her money, telling her the truth, that it is what her Husband would have done in your position.