Hi Manoj,
Looking at your requirements a family floater policy will suit you ideally. However, as you mentioned your father is suffering from diabetes and requires coverage for the same, I would like to bring to your notice that diabetes in this case will be considered as pre-existing and will not be covered immediately by the insurance company. A pre-existing disease is covered by the insurance company usually after 4-5 years of continuous coverage with them.
I have a family floater policy from Max Bupa which provides coverage for pre-existing diseases only after 48months (4 years) of continuous coverage with them. Also the policy is very affordable and is equipped with impressive features like any age enrollment, assured renewability for life, maternity benefits, highest sum insured of up to Rs 50 lakhs, etc. I would personally suggest you to go for Max Bupa Health Insurance policy. You may visit MaxBupa.com for more information on the same. I hope I have helped you with your queries.