Is ammonium molybdate an acid or base?

Methane can be protonated by superacids to the carbonium ion:

H+ + CH4 -> [CH5]+

So methane is a Lewis base but, like helium, it is an exceedingly feeble proton abstractor.

and

They can lose a proton, but their tendency to lose a proton is so small that the term acid would not normally be applied to them.