Of course, Joan was indeed alone, but her three contracted spirits would be there with her.
When she first visited Ainsley, so as not to scare the newborn spirit, Joan left her three spirits outside of the portal leading to the Blood Clan's Kingdom.
But now that she had to go out, she wanted to bring the three spirits to protect her from unforeseen circumstances.
Zenith didn't know that Joan and her three spirits would bring him a surprise that he wouldn't want to receive.
After Joan sent the message, Jake also saw this and didn't know why but felt that his grandma would certainly come alone.
However, alone in the sense of...human beings. How could a shaman master not bring spirits with them?
Celestials were indeed called angels because of their wings, but even so, they couldn't see spirits if they weren't shamans.