My question involves landlord-tenant law in the State of: NY

A friend of mine rented an apartment for a couple of months in east coast US. The rental agreement specified two months notice.
My friend and another roommate both lost their jobs and vacated the apartment without notice to the landlord.
Now they have received legal notice to pay for the debt. No breakup of the debt has been provided.

Can anyone clarify what is the recourse available to my friend:
a. pay the amount demanded
b. if the amount is paid, will it be considered as acceptance of guilt
c. will there be additional claims if this amount is paid