An Uninvited Ghost by E.J. Copperman.
In the second of the Haunted Guesthouse mysteries, Alison Kerby welcomes the first paying guests to her home.
Alison is now a licensed private investigator, having agreed to help resident ghosts Paul Harrison (former P.I.) and Maxie Malone (former owner of the house) with the occasional investigation provided they'd appear for her lodgers twice a day. These particular guests are the first group (hopefully of many, if their experience is positive) from a company offering unique vacation experiences to seniors.
Meanwhile, Scott McFarlane, a ghost acquaintance of Paul's asks him to investigate a prank he was asked to play on an elderly woman, which he fears may have resulted in her death. Since Paul is unable to leave Alison's house, it falls to her to find out whether the woman, who turns out to be prominent local citizen Arlice Crosby, is alive or dead.
But Alison's life is nothing if not eventful, and while all this is going on, the executive producer of a reality show called Down the Shore (which sounds suspiciously like an actual reality show that is filmed in New Jersey) that the guesthouse would make a perfect backdrop for the next season of the program. Alison is loathe to agree to his proposal, until she find out how much she'd be paid. Suddenly, her idea for turning the attic into a luxury suite looks much more possible.
All the above details make it sound as if the plot will be a complicated mess, but it isn't. The confusion is fun, and the characters (even the ones who aren't really there) are interesting enough to keep the reader from turning out the light until the final page has been turned.