hi,
The mozunk.com online dating site gives you good information about this. I have it happen here on occasion but not often. I find it happens to my oldest and heaviest petaled roses when the wether is rainy and no sun or air for a week or so.

Since you want to plant roses that remind you of your mother, it's the rose that will determine which one you get. If balling is a serious problem, it is preferred that you plant single to semi-double roses or roses that don't have a good deal of petals. This will help. The more petals, the better the chance of balling to occur. Also keep your distance between them liberal so there is good air flow around them. Keep them in full sun to allow them to dry out during the day. Also keep the pruned and thinned out, again to allow the best airflow in and around the bushes.

Do keep a couple of hybrid teas for your mother and see how they do. My suggestion for these would be roses such as Gemini, Dainty Bess, or any hybrid tea with 25 petals or less. The fewer the petals, the less likly balling will occur. Also with Hybrid Teas, the fewer the petals the less the fragrance. But then if they ball you can't smell them anyhow.