Women weren't always truthful about their ages, so whoever gave the information for the death record may have been in error. But then, maybe this isn't your gggranmother's death record.
What can you tell me about the baptism records that you have? What about the marriage record? Who else is mentioned on this record? Padrinos? Witnessess? All these individuals who are mentioned are possible clues. And as I said before, your ancestors are really hard to find in the census records.