First of all as @Michael Hampton updated that table name start from #sql are temporary tables created by mysql and as per my understanding removed automatically after use. So you should not worry for it.
If only user table is required (For mysql user rights), then follow below steps:
Step1: copy below tables from /var/lib/mysql/mysql path
Note: Check your datadir path with the help of below command, it should be /var/lib/mysql
SHOW VARIABLES LIKE 'datadir';
Step2: Now move these tables to any testing mysql server's data directory suppose /var/lib/mysql/mysql
Step3: Provide rights to mysql for these new files with the help of below command-
chown -R mysql.mysql /var/lib/mysql/mysql/.
Step4: Restart mysql on this testing server.
Step5: If every thing is fine here then take dump of complete mysql database or just user and db tables as per your requirement and restore this to your production server where you are planning to restore your db.
Note: If you want to recover complete data of your system then need more information like what command you execute at the time of problem, after that what actions you took and what is innodb_file_per_table status on your server what files are exist in data directory etc.