Notice: Undefined index: und in include()
Before assigning the values to the field directly you must check if it contains any value or not otherwise you will get the notice like above, try to check the value something like below (the below code is for reference only, you can modify it as per your requirement):

&lt;div class="House_Header_coupon_link"&gt;&lt;a href="&lt;?php
print isset($node-&gt;field_house_coupon_link[LANGUAGE_NONE]) ? $node-&gt;field_house_coupon_link[LANGUAGE_NONE][0]['url'] : ""; ?&gt;"
style="color:#&lt;?php print isset($node-&gt;field_house_coupon_link_hex_code[LANGUAGE_NONE]) ? $node-&gt;field_house_coupon_link_hex_code['und'][0]['safe_value'] : ""; ?&gt;"&gt;
&lt;?php print isset($node-&gt;field_house_coupon_link[LANGUAGE_NONE]) ? $node-&gt;field_house_coupon_link['und'][0]['title'] : ""; ?&gt;&lt;/a&gt;&lt;/div&gt;


Also it is recommended to use LANGUAGE_NONE instead of und: The language code used when no language is explicitly assigned. Defined by ISO639-2 for "Undetermined".