Xantanla's residence didn't have any guards to speak of. To be more exact, it was basically a big building separated into two parts. One part was a huge open area that allowed very big things to fit inside. That was the area Xantanla used when she was in her demon beast form. The other part was a normal-sized residence for when Xantanla was in her human form.
Although it didn't have any guards, there were still two female cultivators who worked for her on other things related to the house. It was one of them that attended Rean and Roan when they appeared. She then guided the twins to where Xantanla was resting while talking to them, "You want to buy Xantanla's Molten Divine Rock Flowers? I'm sorry, but I find it quite hard to succeed. Also... are you sure you want to even get close to her?"