To be eligible for Parent Migration Program and be given with Parent Visa for Australia, you must pass the "balance of family" test. In addition, you must be sponsored by your child who must be an Australian citizen, Australian permanent resident or eligible New Zealand citizen.
You can apply for a Working Age Parent Visa if you're not old enough to be granted an Australian age pension and you meet the balance of family test. Or if you're old enough, you can apply for Aged Parent Visa.
But if you want to contribute an extra application fee to cover health costs, you can apply for Contributory Parent Visa.