Dog Chow :

Ingredients:
Ground yellow corn, poultry by-product meal, corn gluten meal, animal fat preserved with mixed-tocopherols (form of Vitamin E), brewers rice, soybean meal, dicalcium phosphate, animal digest, calcium carbonate, malted barley flour, salt, potassium chloride, L-Lysine monohydrochloride, choline chloride, zinc sulfate, Vitamin E supplement, zinc proteinate, ferrous sulfate, DL-Methionine, added color (Red 40, Yellow 5, Blue 2), manganese sulfate, manganese proteinate, niacin, Vitamin A supplement, brewers dried yeast, copper sulfate, calcium pantothenate, copper proteinate, garlic oil, pyridoxine hydrochloride, Vitamin B-12 supplement, thiamine mononitrate, Vitamin D-3 supplement, riboflavin supplement, calcium iodate, menadione sodium bisulfite complex (source of Vitamin K activity), folic acid, biotin, sodium selenite. O-4101

It doesn't have sugar listed anywhere which IMO is better than the Beneful, where sugar is high on the list:

Ingedients:
Ground yellow corn, chicken by-product meal, corn gluten meal, whole wheat flour, beef tallow preserved with mixed-tocopherols (source of Vitamin E), rice flour, beef, soy flour, sugar, sorbitol, tricalcium phosphate, water, animal digest, salt, phosphoric acid, potassium chloride, dicalcium phosphate, sorbic acid (a preservative), L-Lysine monohydrochloride, dried peas, dried carrots, calcium carbonate, calcium propionate (a preservative), choline chloride, vitamin supplements (E, A, B-12, D-3), added color (Yellow 5, Red 40, Yellow 6, Blue 2), DL-Methionine, zinc sulfate, glyceryl monostearate, ferrous sulfate, niacin, manganese sulfate, calcium pantothenate, riboflavin supplement, biotin, thiamine mononitrate, garlic oil, copper sulfate, pyridoxine hydrochloride, folic acid, menadione sodium bisulfite complex (source of Vitamin K activity), calcium iodate, sodium selenite.

I wouldn't worry too much about it if it's just a temporary change. You might consider making a chart and show your folks how much you're feeding of the 'lower quality' food and how much you're spending on it. If you can talk them into feeding a premium food for a short while, you can compare the two and they can see that they'll probably spend more on the cheaper foods with fillers.

Hope your Dad's doing good.