Geez. If nothing sensitive was taken, format the hard drive, reinstall the OS and employ some security. As in stronger passwords and locking down his network
New habits need to be created. Most of us do not understand what on line security even means...the way you choose passwords is important. How many times you use them for different accounts. It should be once per account and nothing that relate to you as in birthdays, phone number or anything with little to no difficulty factors.
There are apps that generate random password for you that you need to write down to not forget. Store those in a safe somewhere you control and out of reach.
And there is a function that I only have limited understanding but a quick search on the topic will explain very well; 2 factors verification in the setting of your sensitive accounts like your bitcoin account or email account were you get important informations. They are to have you need 2 different passwords in order to log in your accounts. There is also a program you can get that randomly generate the second passwords every 20 sec... research it up its worth it.
I will also attach a link shortly for you, not now cause I'm a bit busy...