EMERGENCY! My dad's macbook pro had a black screen and a message!

This scary incident just happened a few minutes ago, i was informed by my mom saying that my dads macbook pro had been turned off out of no where and if had a black screen and a message appeared saying something close to this: "Your information is being sent to hackers". I am very scared since my dad has no skill in macs, including me since im a windows user. There was no power outage or anything, he has a laptop not a desktop. I did have alot of enemies on my windows computer since we have all the same IP address. These enemies always threaten me that they are going to hack me, i do not know who did this, this is not a joke, i am very scared for all my family info and everything, i am not sure what to do since im freaking out, i am NOT a mac user, i used to until i got my first windows computer. Please i need answers fast on what to do, again this is not a joke, i heard its rare since macs rarely get viruses. My dad has been clicking on many emails, i asked him if he clicked on any of the Click me to get 500 dollars! or anything like that, he said he doesn't know since he has a business and he does read many emails and clicks on them. If i just get so many answers to call 911 or anything like that, i am not doing that, i need something else, i researched this, i never encountered this or any luck on if this happened to anyone else. Please give me answers ASAP

Here is some info about the computer:

It is a Macbook Pro. with about 500 GB disk.

It uses i think Mac OS X Yosemite 10.x

Including a Retina display.

Here is some stuff extra info:

I do have many enemies online.

We use Verizon FiOS

I have a hacker friend but never talks to me,

He never double checks on the emails he clicks.