Facebook monetization eligibility check has been moved to Creator Studio where you can see the complete detail about the page and also able to see if there is any violation / breaches on the page.
Before moving ahead it is necessary to make sure you are the admin on the page not editor or analyst, go to how to check admin role . If you are the admin follow these simple steps :
Go to:
Creator Studio https://business.facebook.com/creatorstudio >
Click the Monetization , then Overview
– No Monetization Breaches

– Monetization Issues
If there is any monetization issue on the page you won’t be able to apply for In-Stream Ads until the issue removed from the page.

– Check what are Breaches on my Page
Facebook page policies are strong and everyone need to follow all the Facebook standards to keep page monetization on always. Yes you need to follow all the term and conditions from the day one and the best way is to always have your own content. Otherwise you may face different kind of breaches on your page, Limited originality of content the most common breach that comes when you copy any content from other pages without any permission.

– How to apply to remove Monetisation Issues
You are able to send a request to Facebook Support to remove monetisation issue from your page and let you make eligible for monetisation again.
To apply goto:
Creator Studio >
Policy Issues > Click on Requestion Another Review

This will redirect you to a appeal form where you need to provide detail about the page and issues. You need to make sure you have removed all the mislead, copied, sexual and any other content that you think this may violate the rule, I will suggest you to read Facebook Content and Partner Monetisation before making a appeal.

Facebook team review the appeal and answer within 24 – 48 hours normally but they make take more time depend on the number of queries they received. Here is the URL where you get response from Facebook :
https://www.facebook.com/support?ref=contextual , you can see all the issues and your responded too.