If you are a PR then consider applying for a super visa, procedure is more or less same, she will need to undergo a medical exam and will need to purchase insurance before applying for visa (insurance is refundable in most cases).
You need to write an invitation letter, provide proof of your job and bank statement just to strengthen your case, your mother will need to provide her bank statement and prove strong ties with home country in case of visit visa. In case of super visa emphasis is on your finances rather than the visitor's finances.
