i would like to share my experience..when i came for landing in 2019, i happen to meet two old ladies who was also from my state…we were in the same flight n adjacent seats…they didn’t even speak english..upon arrival at pearson airport they asked. me if i could help them n i said yes(i already helped them filling those arrival forms in flight), at the immigration point the officer asked me if we are same family for which i said no, n i’m helping them more like a transalator as they don’t know english n how to do these stuffs..for this the officer replied if u r not family u can’t help, n if u still do it your immigration also will be in trouble! so i had to step back
what i have to tell you is that, than waiting for someone’s help, please explain everything in detail to your mom(tell her she can ask for a translator), secondly at immigration PRs n citizens goes in one line n visitors are in another line(even if someone here volunteers to help they have to be a visitor, n also to be in airport at the same time as your mom!), there are plenty of youtube videos available abt immigration process in the airport you are landing, show that to your mom in advance n let her have an idea abt what to expect n were to navigate
All the best