Good Morning and welcome. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
It is very important that you take this puppy directly to your vet for an exam. This blindness may be treatable and the unsteadiness may be due to the heavy wormload. Your vet can tell you if treatment will be effective so thsi puppy has a good quality of life or if this puppy will not respond. I would not take this poor little Milo back to the owners since they are obviously not good dog owners.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please Reply so I can clarify for you
Sincerely, Dr. Loretta