This code should give you full test coverage:

@isTest
public class emailCon1_Tc
{
    static testMethod void testMthd() {
        String email = '[email protected]';
        String lastName = 'YYY';
        Contact c = new Contact(LastName = lastName, Email = email);
        insert c;
        emailCon1_Tc ec = new emailCon1_Tc();

        System.assertEquals(1, ec.con.size());
        System.assertEquals(c.Id, ec.con[0].Id);

        System.assertEquals(lastName, ec.m.get(email));
    }
}

The reason you are not getting full test coverage is because you are not inserting the Contact record, so the code would not of been iterating over the for loop in your code.

This code should give you full test coverage:

@isTest
public class emailCon1_Tc
{
    static testMethod void testMthd() {
        String email = '[email protected]';
        String lastName = 'YYY';
        Contact c = new Contact(LastName = lastName, Email = email);
        insert c;
        emailCon1_Tc ec = new emailCon1_Tc();

        System.assertEquals(1, ec.con.size());
        System.assertEquals(c.Id, ec.con[0].Id);

        System.assertEquals(lastName, ec.m.get(email));
    }
}