Always a pleasure to help out. Being of the same age as your mother, knowing the pain caused by long term smoking, how hard it is to quit, and the loving concern you expressed and the lengths you going through to help your mom, brought a tear to my eye. Am glad your local B & M has these in stock, they have been hard to find, so that was one of reasons for my offer.
I had been a smoker for 27 years until my first e-cig-a-like came to me. Was one of those try for free scams but never the less it showed me that there was a way to not smoke. I finally found the ECF where journey in the world of vape really began. In my quest for more vape satisfaction I procured a Provari, needed more, than entered the rba world. I now DIY juice, rba's builds, journeyed into Mechanical mods and the sub ohm zone. I've only been a vaper for 9 months, 5 months since I joined the ECF, but have made long strides into my journey and have acquired a fair selection of quality mods and rba's.
Hopefully you will find something that will work well for your mom that will allow her to not smoke and give her the satisfaction she needs without a nasty cough. I know it can be done because I did it, along with many other of all ages. You probably will want to start her off with the higher ohm coil, it will be slightly cooler and not cause as much throat irritation, but the Nautilus does provide a fairly cool and smooth vape even with the 1.6 ohm coil heads. Since it looks like your are using you ego non vv bats for her, once she acclimates to vape, and needs more volume vapor and throat hit, you can always go to the lower ohm coils, up her nic level and adjust her VG/PG ratio.
For me, I found high PG juice harsh and scratchy on the throat. I now vape at 70-80% VG and love it, nice smooth flavor, works great for me. When I was using an ego and a PT, I needed 18-24 mg nic, smoked camel filters at about 30 smokes a day. After upgrading, learning to build, and increasing my watts vaped at, I have had to lower my nic to 12 mg. The better the gear the more efficient the nic delivery is, so one has to keep that I mind when trying to find the right nic level.