Machine code and assembly are different languages
If you write a program in assembly, therefore, you can submit it two different ways: you can either submit the source code you enter into the assembler (an assembly language solution), or else submit the object code or executable that you get out of the assembler (a machine code solution). The header of your post would be, e.g., "x86 assembly (gas)" or "x86 machine code (Linux)" in the two cases.
Machine code solutions should typically come with a disassembly in order to make them easier to read, although that isn't technically speaking required.
Note that except on DOS (where the .COM file format has very little boilerplate), it's probably going to make more sense to submit a function rather than a full program due to the vast difference in boilerplate amount. In this case, you only have to submit the machine code for the function itself (including the ret or equivalent at the end!), rather than an entire object file.