I would like to recommend you this amazing place for staying in Madrid.
The hostel is located on the center of the city. The Prado museum- 15 min walking, the Teatro Real - 15 min. A lot of cafés and restaurants nearby.
Room. The room is small but cosy. With your own separated bathroom. It’s a huuuge advantage!
The landlord - is amazing! She can help you with any kind of issue. Very polite, inteligente and kind!