REGEX-Escape for: <input type="hidden" id="akismet_comment_nonce" name=&qu...

Your Input:
Result, the escaped string:
\\<\/p\>\

\

What must the escaping look like for:
<input type="hidden" id="akismet_comment_nonce" name="akismet_comment_nonce" value="81a0535e35"/></p><p style="display: none;"><input type="hidden" id="ak_js" name="ak_js" value="149"/>

The excaped text for use in a regex is:
\<input type\="hidden" id\="akismet_comment_nonce" name\="akismet_comment_nonce" value\="81a0535e35"\/\>\<\/p\>\<p style\="display\: none;"\>\<input type\="hidden" id\="ak_js" name\="ak_js" value\="149"\/\>