One of the documents you will file is the I 864, an agreement for you to financially sponsor them.
Medical Insurance etc varies a lot by the State they will be living in, now most people of that sort of age will be on Medicare. Under current rules they will have to wait for 5 years before they can buy in, as they have not contributed to the system they will not get the basic element for free.
Normally the intermediate option is through the ACA, buy through the State exchange, so that varies significantly.
Any Insurance they can access obviously does not cover everything, one of the big issues can be long term care.