Why hasn’t my friend received his return? Even though we filed it last year, and paid off recent tax files.

Are you talking about their tax return or their tax refund?
 

If you are talking about the refund - you'll have to contact the CRA to ask why it hasn't been send yet. This CRA page lists ways that your friend can check her refund status: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/refunds-status.html