Medicaid wants to get reimbursed for overpayment

My father was receiving medicaid until January of this year. He just received a letter in the mail saying he was ineligible from 2012 to now because of money he had in an account. They are now saying they should be repaid almost $70k. How can they go about getting paid? Is there a way to not pay this or negotiate the amount? My father is not in the best state of mind. He was unaware of the funds, when we realized they were there we used them to pay for some repairs to the house, to repay my siblings for expenses they've paid for over the years such as car insurance, home owners insurance, property taxes and other expenses.