Considering her advancing age, first we need to see what all foods she can tolerate. As you have said she cannot tolerate solid foods, you can only give her semi-solid and liquid diet. Among semi-solid foods, you can give porridges made out of rice/broken wheat/oats either prepared in water or milk. You can give sweetened porridges if she is not a diabetic or else give salted ones. Does she have teeth? If chewing problem is present, then give her thin porridges or else you can give thicker consistency porridge as desired or tolerated by her. Can she digest milk well??? You can also give buttermilk ( add water to whipped curd), soyamilk if she has lactose intolerance. Signs of forgetfulness maybe due to age-related dementia. You can give mixed vegetable soups prepared at home including vegetables like tomatoes, spinach, beetroot, carrots, onion and garlic (for flavour). You can also give her spinach and lentil soup, mutton/chicken soup if she is a non-vegetarian. If milk is well-tolerated, then you can give her fruit milkshakes like banana, mango or chickoo milkshakes. Add skimmed milk powder to milkshakes for extra energy and proteins. Fruit juices can also be given like orange juice, pomegranate juice, pineapple juice, sweet lime juice with added sugar or glucose (if she is not a diabetic). Hope this will enable you to feed her well and take care of her nutritional requirements also. If you need more advice or assistance, you can always ask me again.