Welcome to Yorkie Talk. A lot of vets want dogs to stay overnight after neutering/spaying. I wouldn't do it if there is not 24 hour staff.
You can talk to your vet's office and insist on taking your pup home. If they refuse, then I would seek another vet's office.
Our former vet who performed Max's surgery said I had to leave him overnight. When I dropped him off, I threatened to bang on the windows all night until they gave me my dog. Turned out that Max barked his way out. The office called me at 4 pm and told me to come get my pup.
