Survivors Benefits: Is It Too Late to Appeal

My husband died 5 year’s ago. I applied for survivor benefits for my 3 children and myself a month after he died and was told he was denied because he had only 9 working credits and needed 15. And he earned those credits many years back. I left the ss office and went on with my life trying to provide by myself for my children. One day I was researching the ss website and read that there is an exception to the rule that one may be eligible if they have only 6 working credits but they earned them only 4 years prior. So my question is since his death was 5 years ago and I never appealed can I still appeal or reapply. I really need some help and he was murdered him leaving was definitely not planned

Survivors Benefits: Is It Too Late to Appeal