Here is how to create 2 columns in mobile view.

Step 1
Go to the decision tree scripts as shown in the image below.

Step 2
Click on the “Add” button under the Decision Tree Scripts.

Step 3
Add the code below.
<style>
@media (max-width: 767px){
.answer-col {
margin-left: 0!important;
margin-right: 0!important;
width: 50%;
float: left;
}
}
</style>

Step 4
Save and publish.