Our EC2 system has been hacked and our custom Database deleted. Can we recover an earlier version of our instance without a backup

If there are no EC2 snapshots at all, restoration is not possible.
Even if we ask AWS to restore the data, it would be difficult to do so because there is no data.

We recommend that you regularly back up your EC2 using AWS Backup or similar software so that you are prepared to deal with such an eventuality in the future.
https://docs.aws.amazon.com/aws-backup/latest/devguide/whatisbackup.html

Are you also getting a dump file of the database?