There are four subway lines, D, F, N, Q that stop at the Still Avenue terminus just a few blocks from the Brooklyn Wall. It will take at least one hour. There is always work on the subway lines, so you should check before choosing a line. I would imagine the hotel can check on-line for you.
To get to Peter Luger's:
Take the 6 train to Broadway-Lafayette and transfer to F Train downtown to Delancey Street. Go upstairs and transfer to the J, M, Z Train over the Williamsburg Bridge to Marcy Avenue (First stop over the bridge). Walk on Broadway towards the East River to Peter Luger at 178 Broadway.
On the way back take the J or Z to Chambers Street and transfer to the 4,5,6 at Brooklyn Bridge. There is no uptown transfer at Broadway Lafayette.
Remember Luger's only takes cash, so bring lots of it.