I'm taking SS at age 70. When I die, will my widow (who started her benefit at 62) be eligible for the delayed credits I earned?
Yes, if your wife qualifies for widow's benefits her benefit rate would include credit for any delayed retirement credits (DRC) that you earned by waiting past your full retirement age (FRA) to start drawing your benefits (https://secure.ssa.gov/apps10/poms.nsf/lnx/0300615706). However, if your wife starts drawing widow's benefits prior to her FRA her widow's rate would be reduced for age. The fact that she started drawing her own benefits prior to FRA would not cause her to receive a lower widow's rate, though.