I think human remains should always be treated with respect, though I don't think that precludes putting ancient mummies on display in museums. I don't know whether archaeologists have a code of conduct about dealing with human remains - I'd guess that they do.
A former vicar of mine, who went to a parish on the Isle of Wight after leaving us, told of an Anglo-Saxon burial site in his parish which was discovered during building work. The skeletons had to be moved, and he and others, after determining from the dates that the dead had been Christians, not pagans, devised a short reburial service, which incuded a recital of the Lord's prayer in Anglo-Saxon. People found it very moving, apparently, and I can believe it.