"What is your name?"
Translation:Nama kamu siapa?
Both are correct.
"Siapa nama kamu?" is more grammatically preferable. But in spoken language, "nama kamu siapa?" is sometimes used.
The form "Object - Question" is mostly acceptable in spoken Indonesian, just like the "Question -Object" form. For example:
"Kucing kamu berapa?" (How many is your cats?)
"Caranya bagaimana?" (How/what is the way [to do something]?)
"Itu apa?" (What is that?)
It is incorrect.
Nama means name, meanwhile siapa means who, and the -mu suffix here denotes possession of the 2nd person singular.
So what you wrote literally means "The name who is yours" which doesn't make sense. It should be "Namamu siapa?", which literally means "Who is your name?"