For a short period (3-4 days), the Poon Hill trek or other similar options in the lower Annapurna region would be ideal. However, you must be extra cautious when taking young children, as young as 3 or 5 years old, on treks that involve rough terrain, challenging uphill climbs, and steep descents And, all treks in Nepal are characterized by such terrain and challenges. I do not recommend & operate high altitude treks (in excess of 3500 metres above sea level) for young children. Treks in the Lower Annapurna regions stay below 3200 metres.
Esp. on Family treks involving children below 10 years old, you'd need a larger crew with Assistant Trekking Guide (in addition to the main guide) and additional porters to piggy-back the children or carry them in improvised Nepali 'doko' (basket) at times when it gets physically too strenuous for them or on potentially risky/ tricky trail sections.
When it comes to trekking equipment, you'll need to pack all items, except for sleeping bags and down jackets, which are available for hire. Smaller-sized down jackets for younger participants are not available for hire so you'd need to bring these too.
