The purpose of visit refusal reason generally means that your mother has not shown strong enough ties to her home country. It means IRCC has concerns she plans on remaining in Canada long term.
- How long a visit did she request?
- Does she have previous travel to countries requiring visas such as the US or UK?
- How much did she show in proof of funds to cover her visit?
- What did she show as proof of ties to her home country (e.g. property, job, etc.)?
- Is she living in her home country or as a temporary resident in a different country?