Assume red bottle is made by Menes making statement false, now we can safely assume only one bottle was made by menes, because we already assumed that the red is menes bottle, the other two must be bottles made by Nil. But this wouldn’t be possible as that would give us 2 cures.
On the other hand if we considered the red bottle as having been made by Nil making it a true statement, we can safely assume that we have at least 2 bottles by Menes. Because we are only left with 2 bottles, the yellow and blue bottle can be said to be false statements. Meaning the two are not cures, which would only leave one possibility for the cure *red* bottle.
Cure is in the red bottle