If you are holding a PR, then consider Super visa if you meet LICO
If you still would like to apply a visitor visa for your mother,
- your mother can request a visa for a 3-4 week trip to Canada to meet & spend time with you
- Show her home ties back in India and why she will return without overstaying here in Canada
- Establish her finances - 6 months statement, pension or rental income with receipts , tax returns & CA Report [not mandatory but nice to have]
- Submit a plan of what she plans to do while visiting you in Canada - Ideally some trip bookings or tickets
- Health insurance or travel insurance - not mandatory again
- Round trip flight tickets - not mandatory again but since you already have a refusal for this reason it may not hurt to show a finite travel plan this way
Good Luck on your application