The first step in this process is in the construction yard, inside the foreman's office at the left. Float on in there and see what you can find.
There are a number of interesting things in here, but the two you really need to have Joey notice are the "Seagram Realty" poster and the letter on the desk from Harriet Sherman.
Go back outside and switch to Lauren, then go home and look up both names.
There's no listing for "Seagram Realty," but there is for "Harriet Sherman." Call her and tell her you're from Seagram; she's delighted to hear she's going to get her $60 finally.
Grab the money from the "Rainy Day Jar" next to the door and go off to see the greedy old -- I mean, the thrifty senior. Harriet will tell you a great deal, including the ghost's name and circumstances, and give you a letter and a photo.