menthol is a treatment for Tracheal mites, Bt (Certain) is a treatment for wax moths, and Oxalic acid is a treatment for Varroa mites.
It might be more cost effective to combine treatments for different pests into one application but then extreme care must be taken to insure that the combination of "cures" doesn't become more toxic than the pest. To my knowledge there has been little or no research on combining the application of treatments for the 3 pests listed so I'd not recommend it.
However, using a grease patty to impart menthol, pollen, and sugar to the bees at the same time has bee practiced for sometime. But in this case you are treating a pest with the grease and mentol and addressing the nutritional needs of the hive with the pollen and sugar. See the difference?