Have your parents lived in the same home since you were a child? How about their neighbors? Have your parents moved recently? Do you know their neighbors? Do they know you?
Especially if you live away from your parents, even if it’s a short drive, it may be a good idea if you get to know their neighbors and swap phone numbers with them. This is hopefully, if you feel that they are trustworthy people. If anything is wrong, you may not be able to assist them quickly, but they may be able to. Or if they see something is not right, once they have made a connection with you, they may feel more comfortable to watch out for things and also to reach out to you.
If you are not already familiar with their neighbors see if you can take them a small get-to-know hello gift with your contact information and see if they are willing to share theirs. This may be a slow process but one that you may wish to start sooner than later.
Also, if you don’t know your own neighbors, this may be a good time to start yourself!