Try something like Innova Evo canned food. It's very high quality,
grain free, and higher in calories than some canned foods. Our cats
love Evo, and it's available in several varieties. http://www.naturapet.com

IMO, not trying to start a flame war here, your senior girl should eat
most or (better) all canned food diet. A high-quality canned food
won't have carbohydrates (which cats don't need anyway), good protein,
and moisture (always good for all kitties). At her age, the more
nutrient-packed the food, the better off she'll be.

Rene