Instead of custom code, we can also use custom validation and add validation as for those other 16 rows "Not applicable is not selected"

Add those text in span class with some class name (like in below code "op1, op2, op3..") where you need to show the radio buttons and do not add any span class for other options
And add the below codes as per your matrix layout,
// If you have applied border to matrix question
jQuery('tbody tr').find('td:last-child').each(function(){
jQuery(this).find('.q-radio').css('visibility','hidden')
})


jQuery('.op1').closest('tr').find('td:last-child').find('.q-radio').css('visibility','visible')
jQuery('.op2').closest('tr').find('td:last-child').find('.q-radio').css('visibility','visible')
jQuery('.op3').closest('tr').find('td:last-child').find('.q-radio').css('visibility','visible')
jQuery('.op4').closest('tr').find('td:last-child').find('.q-radio').css('visibility','visible')


// If you don't borders applied to matrix question
jQuery('tbody tr').find('td:last-child').each(function(){
jQuery(this).css('visibility','hidden')
})


jQuery('.op1').closest('tr').find('td:last-child').css('visibility','visible')
jQuery('.op2').closest('tr').find('td:last-child').css('visibility','visible')
jQuery('.op3').closest('tr').find('td:last-child').css('visibility','visible')
jQuery('.op4').closest('tr').find('td:last-child').css('visibility','visible')