How to compare acidity in the following aniline derivatives?
Taking the case of ortho and meta in which you have confusion: 

The acidity of aniline will increase if there is a electron donating group in the compound to stabilise the conjugate positive acid formed.

Since OMe is shows +R and -I effect, it is a net electron donating group as +R effect generally dominates over -I.So in case of ortho it is able to show electron donating nature due to +R effect which makes it more basic than the meta isomer which shows electron withdrawing effect due to only -I effect as +R effect will not affect from meta position.