Step 1: Identify the event in question.
The 28th Conference of Speakers and Presiding Officers of Commonwealth Countries is a parliamentary gathering of Commonwealth nations.
Step 2: Eliminate cities that do not fit.
Surat, Mumbai and Madurai are not typically chosen for hosting such high level parliamentary conferences.
Step 3: Recall the host city.
The 2026 edition of this conference was held in New Delhi, India's capital and usual venue for such diplomatic gatherings.
\[ \boxed{\text{New Delhi}} \]