Is there a signed lease?. Was the lease not renewed?.
If the lease was not renewed and they just do not want to move out, as a poster told you, the eviction process is very, very sloooooooow.
Now, since they are playing hard ball with your friend, your friend CAN play hard ball with them. This is what a friend of mine did a few months ago to some people that refused to move from his home, after begging them for 4 months to move out: He contacted 5 "tigueres' friends of his and they moved all his furnishing into the house. The 5 tigueres moved in and made the tenants' life miserable, playing loud music at all hours and having all their friends come over for gatherings. Now imagine 5 tigueres with no shirts on and not letting you sleep every single day with their loud music and cursing and being loud!. Yes, you got it, the tenants moved in 2 days!!!. That is exactly what I would do if my renters give me any type of problems, considering that the lease was not renewed. Good luck.