please... I need your help

hello ..my name is Alkassem and I am from syria.
my father is a doctor who worked in Norwich city in England for 8 years in the 80s ,he is a fellow of the Royal College of Physicians.
during his 8 years he paid taxes and was very beneficial for his community.
in his last year there he received a call from his mother (my grand mother) telling him that his father had been in a car accident and his life in serious danger. so he flew back to syria and unfortunately his father didn't survive. my father then couldn't go back to England and had to stay to take care of his mother .
My father had met all the requirements needed to apply for UK citizenship but due to the circumstances he never did .
so my question is : can my father now do any thing to apply for the citizenship???

To qualify for citizenship, he needs to hold Indefinite Leave to Remain AND have 5 years residence in the UK immediately before applying for citizenship.

So no, it appears he does not qualify.

On what visa was he in the UK??