• We use "at" with an address to specify a location or a building number on a street.
• In contrast, "in" is used for general locations like cities, states, or countries.
• "Over" is typically used for positions above something or across something else.
• "On" can be used with streets in contexts like "living on a quiet street" but not for specifying a building number.

Therefore, "at 45, Dhauladhar Street" is the most natural way to express an address with a building number.