Diet-wise I'd say avoid any chemicals or anything out of a packet. No caffeine, sugar, sweeteners or processed food whatsoever. Two litres of filtered water per day. If she has meat, make it organic and in small portions. Take digestive enzymes to help break protein down into the amino acids needed to repair tissue (many elderly people have trouble with this, and the undigested proteins can cause inflammation). Take a good quality antioxidant and probiotic supplement - best see a nutritional therapist (NOT an NHS dietician, they are usually clueless) for advice on what to buy.
Manuka honey has been found to heal ulcers in trials, make sure you get the right type and strength though. It is possible to buy dressings impregnated with manuka - again, see nutritional therapist eg someone ION or BANT registered. Good luck.
