If it is in the lease that there is a fee for dogs, the lady should definitely be charged that fee.
It is a puppy, therefore not a certified assistance animal, which means the lady cannot use that as an excuse.
She wanted a puppy, she got a puppy. If anyone else wants and gets a puppy, they are charged, this lady should be too. This is not a service animal we are talking about (it would have to be certified, which doesn't happen as a young puppy)

Also, I have a 10 year old with severe ADHD, a puppy would be a nightmare for her, because as is the nature of adhd, she is unorganized and forgets stuff.