The first thing your need to check what type of visa she has. Regular Visa (good for 6 months or until the date notes by the CBSA officer on the arrival stamp) or SuperVisa (good for 2 years or until the date notes by the CBSA officer on the arrival stamp).Thank you @Paul09 for your response. But if the application to extend the stay is withdrawn, it would mean she stayed over 6 months in Canada without approval. Please advise.
I just want to make sure this shouldn't impact her PR process approval or when they land in Canada on PR.
Now to answer your question, if you applied for Extenssion before the expiration of valid status, you are good.
Application withdrawn
If the extension application is withdrawn, on the date the withdrawal is registered, there is no longer a pending application for an extension. Therefore, the period of authorized stay ends on that date.
Sourse:
https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/temporary-residents/visitors/implied-status-extending-stay.html