Memorializing an account also prevents anyone from logging into the account. Even a family member would be prevented from managing this like any other estate issue...
The crappy thing is a friend, wittingly or unwittingly can notify Facebook about any person being deceased and they will memorialize the account, it is unclear to me if they will ask the family.
This from the Help section of FB:
"A deceased person's account is appearing in "People You May Know." How do I report this?
Please report this information here, so we can memorialize this person’s account. Memorializing the account restricts profile access to confirmed friends only. Please note that in order to protect the privacy of the deceased user, we cannot provide login information for the account to anyone. We do honor requests from close family members to close the account completely."
If you want a copy of your deceased loved one's Facebook as it was before they died and before anyone might report them as deceased... for any reason -you can click a link and get a copy of all of it in a single download.
This feature is only available after confirming the password and answering appropriate security questions. You have to know the password and security question answers in order to do this...
Here are the FB instructions:
"How can I download my information from Facebook?
You can download your information from the Account Settings page.
Open the Account drop-down menu at the top right corner of Facebook and choose Account Settings.
Scroll down to Download Your Information and click learn more.
Click the Download button on the following page.
Because this download contains your profile information, you should keep it secure and take precautions when storing, sending or uploading it to any other services."
These things are a part of your memories, but you are not in 100% control over them, so I suggest you look into preserving it in some way for your peace of mind.