The smell you're smelling off from your mom are all combinations of the cat and her room.Sometimes, lighting a candle (even just lighting up a match) gets rid of the smell. Being outdoor for a few minutes can air out the smell. You could tell her you're embarassed about how she smells when she comes over. Since she's used to the smell, you may have to be HONEST W/HER and tell her she does smell. I don't think there's much you can do to improve, unless she's willing to get rid of her cat (?)
When we bought our house, everything smelled like cigarette. The walls, curtains, blinds, rugs. The minute you walk in, and even after they've left 6months later, the house still smelled. We washed all the panellings and ceilings, removed and replaced curtains, throw away the blinds, got new carpeting and opened all windows even repainted bedrooms. Finally, it no longer smelled.