Per your other post it appears that you'll be visiting in November, so you'll need to get an early start each day to maximize your available daylight - days will be short. Most here suggest staying near, but not necessarily in, Killarney, which can see traffic snarls virtually any time of year. I agree with the advice about going clockwise one day and counter-clockwise the next. Do stop by the Gap of Dunloe - one of the prettiest glens in Ireland - for a scenic walk (about 3.5 miles each way to the head of the glen) or one of the jaunting cars as mentioned earlier. There are organized tours based in Killarney that involve a boat trip across the lake to Lord Brandon's Cottage, boarding a jaunting car there for a one-way trip thru the Gap, lunch at Kate Kearney's Cottage, and then a bus or van back into town. Might be something that your Mother would enjoy. Do pick a sunny day though - would guess that it would be pretty miserable if it's cold or rainy.
And include the detour out along the Skellig Ring Road on one of your days. Tour buses don't go out there which makes for an altogether pleasant excursion. Stop by the Kerry Cliffs for a photo op and a short stretch of the legs, then head down the street to the Skellig Chocolate factory - a destination in its own right in our opinion. Further along is the scenic village of Ballinskelligs, where you'll find the ruins of an old abbey and a very nice stretch of beach for wandering ... or maybe a picnic on a sunny day.