To qualify you can use Social Security, retirement funds, pensions and even dividend and capital gain income. A last option may also be a reverse mortgage depending on his goals. I would be happy to meet with you and discuss options. Feel free to call me any time.
So sorry to hear the loss of your mother and I hope your father gets the help that he deserves in this difficult situation!
I'm not sure what you mean by a remortgage, refinance or something else. I can give you the names of a couple of lenders that could help your father. Please feel free to contact me directly.
Contact the county assessor on the assessed value issues.
1) your father wants to borrow additional funds to be added to the present mortgage, or
2) there is no present mortgage and your father now wants to borrow against the home.
The advice about a reverse mortgage is good. That is usually done where there is no present mortgage. The bank loans a fixed amount of money, using the present home as collateral to secure the mortgage. Payments on the mortgage do not come from your father's job (or other income) because there are no payments until your father passes. Then the total amount, plus interest, is paid b the sale of the home. Any left over money goes according to his will.