JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form-check form-check-inline selectEmailOptionsType">
	<input class="form-check-input selectEmailOptionsTypeInput" type="radio" name="emailoptions_type" id="emailoptions_type_[user_id]_days" value="days">
	<label class="form-check-label" for="emailoptions_type_[user_id]_days">Days</label>
	<input class="form-check-input selectEmailOptionsTypeInput" type="radio" name="emailoptions_type" id="emailoptions_type_[user_id]_hours" value="hours">
	<label class="form-check-label" for="emailoptions_type_[user_id]_hours">Hours</label>
	<input class="form-check-input selectEmailOptionsTypeInput" type="radio" name="emailoptions_type" id="emailoptions_type_[user_id]_none" value="" checked>
	<label class="form-check-label" for="emailoptions_type_[user_id]_none">None</label>
</div>
<div class="selectEmailOptions">
	<select name="emailoptions" class="form-control selectEmailOptionsSelect">
		<option value="" selected="selected">- Please Select -</option>
		<option value="10d" class="selectEmailOptionDays">10 Days</option>
		<option value="6d" class="selectEmailOptionDays">6 Days</option>
		<option value="3d" class="selectEmailOptionDays">3 Days</option>
		<option value="24h" class="selectEmailOptionHours">24 Hours</option>
		<option value="12h" class="selectEmailOptionHours">12 Hours</option>
		<option value="6h" class="selectEmailOptionHours">6 Hours</option>
		<option value="2h" class="selectEmailOptionHours">2 Hours</option>
	</select>
</div>

CSS

.hidden {
  display: none;
}

JavaScript

$(function () {
	$( '.selectEmailOptionsTypeInput' ).on( 'change', function() {
		const select = $( this ).closest( '.selectEmailOptionsType' ).siblings( '.selectEmailOptions' );
		
		if ( $( this ).val() === 'days' ) {
			select.removeClass( 'hidden' );
			select.find( 'option.selectEmailOptionDays' ).removeClass( 'hidden' ).prop( 'disabled', false );
			select.find( 'option.selectEmailOptionHours' ).addClass( 'hidden' ).prop( 'disabled', true );
		} else if ( $( this ).val() === 'hours' ) {
			select.removeClass( 'hidden' );
			select.find( 'option.selectEmailOptionHours' ).removeClass( 'hidden' ).prop( 'disabled', false );
			select.find( 'option.selectEmailOptionDays' ).addClass( 'hidden' ).prop( 'disabled', true );
		} else if ( $( this ).val() === '' ) {
			select.addClass( 'hidden' );
		}
	}).trigger( 'change' );
});