Take a late night walk and put some anti jw literature in your neighbors paperboxes (not mailbox, that is illegal). Print them out from jwfacts.com or find elsewhere. They won't know who put them there but will have some ammunition when mom comes calling again. At least she won't be able to con anybody into joining up. All they see is a sweet older lady, they have no idea the dangers of this cult. Apparently neither does she, same with my jw, sigh.
I know this may seem extreme but it does work to get them (your jw) to stop, at least in your immediate area so you can become friendly with the neighbors and have a normal neighborly relationship without them worrying you and/or mom will be preaching at them. People will assume you and she are involved with the same 'church'. I know, I know it is a kh but non jw's don't know, care or understand why it isn't a 'church'. Heck, they still don't know what to call them! "the jehovah's are at the door again, quick pull the curtains!"
Or, get tough and tell mom in no uncertain terms that the jw stuff must stop or she will have to move on. I know, it is easier said than done. Maybe she needs some chores? she is not too old to mow the lawn, clean, etc... (?) just throwing stuff out there.........