Thank you for your question.
Claiming a person as a dependant does not mean they don't file their own income tax return. Everyone who earns income needs to file a personal tax return, even when someone else (for example, a parent or grandparent) claims them as a dependant.
Please follow these links for more information.
Who can I claim as a dependant? https://turbotax.community.intuit.ca/questions/1189977-who-can-i-claim-as-a-dependant
Who has to file a tax return? https://turbotax.community.intuit.ca/questions/1190126-who-has-to-file-a-tax-return