By default, Tangerine bank doesn't hide your secret question answer, this hides it.

Hide_Secret_Question_Tangerine.user.js

// ==UserScript==
// @name        Hide Secret Question Tangerine
// @namespace   tangerine.ca
// @description Hide the secret question answer field on Tangerine
// @include     https://secure.tangerine.ca/web/Tangerine.html?command=displayChallengeQuestion
// @version     1
// @grant       none
// ==/UserScript==

var field = document.getElementsByTagName("input");

for (var i=0;i<field.length;i++)
{
        if (field[i].id == "Answer")
        {
                field[i].type = "password";
        }
}