Comparing the age of the game and sound of the module, I find it likely that the music was downloaded from some website or BBS and used without credits. As you found out yourself, it is rather likely that the tune is by beathoven due to the sample text. However, I cannot find any of his tunes which would have a similar size. Of course it's possible that someone took some track by beathoven and exchanged some samples, which would also explain why there are no credits in the sample text (they would have been overwritten in the process).
The only thing I can recommend at this point is downloading all of his works and checking if any of them sound similar to this tune.
