We are given two statements. Let’s evaluate them one by one.
Statement-I: Nepal was a Hindu Kingdom in the past and then a constitutional monarchy in the modern period for many years.
This statement is false because Nepal was a Hindu Kingdom, but it was later a constitutional monarchy only until the king dissolved the monarchy in 2008. So, Nepal became a federal democratic republic, abolishing the monarchy.
Statement-II: The struggling pro-democracy forces achieved their first major victory in 2006 when the king was forced to restore the House of Representatives.
This statement is true as in 2006, pro-democracy forces in Nepal organized a successful movement (the April Uprising) which led to the restoration of the dissolved House of Representatives, weakening the monarchy.
Thus, the correct answer is (D) Statement-I is false, but Statement-II is true.