I think, there will be factorial(4) =24 ways, Since in the question they did not give any information about Source. So any city can be Source and any city can be Destination.
Now Question has been reduced to 4 cities"
A BCD A
A BDC A
A CBD A
A CDB A
A DCB A
A DBC A
Similarly for all cities B,C and D
Answer will be 24 ways.
plz make me correct if i m wrong......