Did some of the Companions suffer from mental decline in old age, and did Allah send down their excuse that they would have the reward for what they did before their minds deteriorated, as stated in "Al-Durr Al-Manthur" on the authority of Ibn Abbas in the interpretation of the verse "Then We rendered him the lowest of the low"?

The Companions were human beings afflicted by illnesses and misfortunes, just like anyone else. Some of them died, and some were killed. There is nothing strange in the fact that some of them lived long lives. Moreover, there is no evidence that any of them lost their sanity in their old age. As for the mentioned narration, the authenticity of its chain of transmission is unknown.