Landlord entering apartment without permission to show off house?

hi, im in queens ny and still have 2 weeks on the lease, my landlord entered without permission to show off the house a week ago with 2 potential new tenants and my 2 little sisters had just got out of the shower when they had entered. my mom was in the kitchen and saw the whole thing and was shocked but instead of starting an argument she put a sign up that ask "please knock before entering". today she walks in unannounced with permission again! we're still on the lease for 2 more weeks, what can we do about this? thanks!