After he passes you will not continue to get 100% of his monthly benefit. I do not know the formula but you will get between 71-99% of his monthly SS benefit. My guess is closer to the 99% than the 71%. You should go to the SS website and try to figure the percent. I am sure there is a formula.
Do a google search on "Spouse surviving benefit if primary did not reach full retirement age" Something like that.