Who's Mistake

Accident happened in the middle of the road 6 people died the driver was a lady of a well known professor of the town and she was driving back home from the school with her two children and  she drives over the farmers family killing farmers wife and his 2 children. Just to avoid the uncontrolled truck profs wife took the car over the foot path and dashed with the farmer's family and dashed the car into a large canal
Few months later the prof got the money of insurance but on the other side farmer was without the family nor did he had any insurance nor any claim settlements he was just cursing to his fate some how this situation of the farmer some how reached to the prof and he got upset as his soul was shaken so he decided to help that farmer but how was the question. He visited him with some money but farmer didn't agreed
Prof went home. Prof decided he will help the farmer but on the other hand farmer was not ready to accept the help from prof. Few years after the incident prof was sitting in the his  lonely house. He was getting weak and weak by the thought that due to mistakes of his wife while a family of a farmer was finished and on the other hand the farmer was working in his farms just to forget this incident both the were trying hard to forget the incident. Prof was thinking how he could help the farmer one day he called the farmer to his house as prof  was about to die he told farmer that he had a last wish and he wanted to that his ashes after cremation should be thrown in the farmers field and if the farmer gets a good yield then his soul will get the rest.