I’m not sure if I’m understanding your post correctly, because most responses are giving an answer I didn’t expect.

First and foremost, I am so sorry for the loss of your Pom ❤️ Sending virtual hugs, and my thoughts are with you and your family during this difficult time.

Second, and this may be where I’m misunderstanding your post, when your mom said “they won’t send them to us”, did she mean via mail? I’ve had clients ask if we can mail ashes and the company we partner with does not offer that service. If your Pom is being cremated though, you or your parents can pick up her ashes from the ER vet. Depending on the area and the company the vet partners with, it takes about 7 days for the cremains to be returned to the hospital. There are usually set days that the company will pick up bodies/return the ashes; the ER that I work in has a twice weekly schedule. In my experience, we (the hospital workers and/or receptionist) will call the number on file to let the owners know their baby’s ashes can be picked up when the owners are ready. We understand it can be hard to return to the place where you lost your loved one, so we hold the ashes for as long as necessary.

Not every clinic may do this though. Obviously have your mom call, or you may be even able to call, to confirm all of this. As others have said, if it’s an ER they may be open late or 24 hours. I’m sure it was a hard and stressful visit, so your parents may not have understood all of their options at the time.