1. IF Father is amicable and willing to sign on documents, THEN apply to the local office of Registrar of Sub-Assurances, for "authorized officer" to visit and conduct registration procedures at home itself, wherein you can take POA, Gift Deed duly executed.
2. IF above is not possible, procure a medical certificate from a Govt. Mental hospital about his condition, and based on said medical certificate, file civil case in local civil court, for declaration and directions to Registrar to register above mentioned Deed /documents. Consequent to all this you will be able to do all what you want to do.
Keep Smiling .... Hemant Agarwal