As I said it delends on HER age when you die, not when she filed. If she files at 62 on her own earnings and you file at 70, and then she switches to her spousal benefit because it is higher, and you die at 72 land she is 78, she still gets your Full age 70 benefit, as a survivor benefit even though she was getting her own and spousal benefit off your earnings for the previous 16years.
This also works for delaying. If you were to file at 62, then her survivor benefit would be your age 62 amount. If she files at 62, and say while you are in the process of delaying you die at 64, and she is now 70, her survivor benefit is your FRA amount, since you never filed.
