Visas to Oman open only through host companies. No host company will open a visa for a girl without buying a tour. Possibility to get a visa can be booking a tour to the hotel at least 4 * (shore) and at least for a week. If you fly unaccompanied by a man, there is still no guarantee. You need to make a reservation in advance so that in case of cancellation there was no penalty for the hotel.

For more information, see the page "Visa to Oman."