The slight error has been to use the prefix mono to name monocarbon.
The compound she is most likely naming is:
[tex]CBr_4[/tex].
As you see, the chemical formula has 1 atom of C, which is likely why she named it mono, and 4 atoms of Br.
The right name is carbon monobromide, i.e. you have to supress the prefix mono, as per IUPAC rules.
