A:
If the matter is indeed as mentioned in the question,
that the husband of the deceased is responsible for the accident since he was driving the car, then he does not inherit anything from his late wife. This is due to the words of the Prophet (peace be upon him) who said:
“The killer is entitled to nothing from (his victim’s) inheritance.”
This is only if he is responsible for the accident. As for the father of the deceased who is senile, it is impermissible for anyone to waive his right in the inheritance and it is not right for him to do so either.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.