If you start noticing the parent or other elderly person is not taking good care of themselves such as not being able to bathe, not eating right, not taking care of the house like they used too.
Are prone to falling and not able to get up. Unable to bathe themselves etc. Then it's time to start looking into a nursing facility.
Some parents and elderly will fight you though when it's time to place them into a care facility and I don't blame them. But sometimes there's no other choice and you might have to get law enforcement involved.
Because if you don't do anything and they get harmed you could be in trouble.