Oh my - I am so sorry to hear of your losses. I was involved in a fire (not my home, and no pets were lost) that was absolutely devastating, so I can only TRY to imagine what you might have gone through!!
How wonderful that your daughter was able to take you in, and more, to allow you to get a puppy - after making the suggestion. A new dog will never replace the ones you loved, but will bring new moments and memories that can help wipe away some of the pain.
This site rates dog foods:
Dog Food Reviews - Dry Dog Foods - Powered by ReviewPost
You can use that to help you make choices about what to try. The suggestion of getting samples was a good one. When you get a new food, if using kibble, you can try at first giving it as a treat. If your dog likes it as a treat, then he might be more likely to accept it as his meal. I feed Lexi Nature's Variety Prairie and Instinct. I just got their raw, but haven't tried it yet.
Good luck, and welcome!