Can the wife of a disabled vietnam veteran receive medical treatment at the VA hospita.?

Only if she is entitled to health care through the VA. Eligibility for care/insurance through the VA varies depending on level of disability rating, the veteran's financial status, and several other factors, all explained on the link Goose provided.

The short answer--if she isn't already receiving any care through the VA, she can't just show up at a VA hospital and say 'my husband is a disabled vet, treat me.'

No.

Not unless she is also a veteran.

no, not at the VA

but they may be eligible for some medical benefits

go here and read.

http://www.disabilitysecrets.com/resources/disabil...

Why dont you call your nearest VA center and ask. How do we know? You must be below a certain income to use the VA.