You were nearly there, I have made your loop use the index E.g {i+1}

Console.WriteLine($"{i+1}. {name[i]} ${price[i]} per night")

The result to use the token {nights} and the calculation to be {price[room-1] * nights}

Example

string[] name = { "Single", "Double", "Luxury", "Penthouse" };
double[] price = { 45.50, 99.99, 165.25, 1095.50 };

Console.WriteLine("Room Types");

for (int i = 0; i < name.Length;  i++)
   Console.WriteLine($"{i+1}. {name[i]} ${price[i]} per night");

Console.Write("\nPlease select a room type 1, 2, 3 or 4: ");

var room = int.Parse(Console.ReadLine());
Console.Write("Please enter the number of nights: ");
var nights = int.Parse(Console.ReadLine());
Console.WriteLine($"\nThank you, the total cost for staying in the ? room for 5 nights is {price[room-1] * nights}");

Console.ReadLine();

Output

Room Types
1. Single $45.5 per night
2. Double $99.99 per night
3. Luxury $165.25 per night
4. Penthouse $1095.5 per night

Please select a room type 1, 2, 3 or 4: 2
Please enter the number of nights: 2

Thank you, the total cost for staying in the ? room for {nights} nights is 199.98

Also note, never use parse type methods for user input, use TryParse type methods to protect against pesky users who can't read instructions.

A more modern approach

internal class Program
{
   public record Room(string Name, double Price);

   public static Room[] _rooms =
   {
      new("Single", 45.50),
      new("Double", 99.99),
      new("Luxury", 165.25),
      new("Penthouse", 1095.50 ),
   };

   private static void Main(string[] args)
   {
      do
      {
         Console.WriteLine("Room Types");

         for (int i = 0; i < _rooms.Length; i++)
            Console.WriteLine($"{i + 1}. {_rooms[i].Name} ${_rooms[i].Price} per night");

         Console.Write($"\nPlease select a room type between 1 and {_rooms.Length} : ");

         int room;
         while (!int.TryParse(Console.ReadLine(), out room) || room <= 0 || room > _rooms.Length)
            Console.Write("Omg, you had one job, follow the instructions : ");

         Console.Write("Please enter the number of nights : ");

         int nights;
         while (!int.TryParse(Console.ReadLine(), out nights))
            Console.Write("Omg, you had one job, follow the instructions : ");

         Console.WriteLine($"\nThank you, the total cost for staying in the ? room for {nights} nights is {_rooms[room - 1].Price * nights}");
         Console.WriteLine("Game over... press any key to play again, or enter to exit");


      } while (Console.ReadLine() == null);

      Console.WriteLine("be gone...");
   }
}

Output

Room Types
1. Single $45.5 per night
2. Double $99.99 per night
3. Luxury $165.25 per night
4. Penthouse $1095.5 per night

Please select a room type between 1 and 4 : fgdsfgdsfg
Omg, you had one job, follow the instructions : 2
Please enter the number of nights : 2

Thank you, the total cost for staying in the ? room for 2 nights is 199.98
Game over... press any key to play again, or enter to exit

be gone...