Social media can become somewhere people share memories and tributes to someone who has died.
There are many tribute sites which exist specifically so that friends and relatives can keep in touch with others who cared about their loved one. This continuing bond with a person who died can be comforting.
Unfortunately, it is also possible to be anonymous online, and sometimes people post unpleasant or abusive messages. If this happens to you there may be procedures you can follow to block users or take down unpleasant messages.