My friends daughter has recently graduated as a radographer in Belgrade Serbia. She is hoping to come to britain to be near her mother, would she have to resit her degree, would she be able to work here as a radiographer, or will she need to take some kind of exam
I (personally) cannot answer your question.
However,this site "NHS Careers" may do so.
You can ring or email them for advice,so they should be able to give you an aswer.
You don't give any information about her immigration staus. That's probably more important than qualifications at this stage. Serbian nationals need to apply for a visa for entry to the UK.
Is she a UK or Serbian national? Does she has a visa to visit or study or work in the UK?
The UK Border Agency has a programme for highly skilled workers. Perhaps she should check her qualifications with them?