At Bernard's funeral, a strange-looking man told Annie that Bernard would live again. According to the Third Doctor, Krashen changed Bernard's history, for money, so that Bernard wouldn't die in the accident.
When the Doctor and Brigadier Lethbridge-Stewart visited the Forbes house, they found him alive, but slowly losing his mental facilities. After Krashen and his time machine were destroyed, Bernard just vanished. (PROSE: Honest Living)