well they can't be. considering the "hey Gondor needs your help, Send your army to Gondor" in the third movie. If everyone was dead, except for the exiles, who exactly would Theoden even had to send in the first place?
so yeah, movie seemingly had just women and children. and yeah, like maybe 20 cavalry it seemed.
Legolas also stated they only had 300 in the first place. The exiles counted 2000. so yeah, the numbers don't really add up that well. If every able bodied man was fighting. probably should have been more then 300.. Particularly when you consider that there were 2000 exiles. so what, Theodan had a standing army of 100? and had 2000 of his own horsemen exiled? lol. Eomor should have just overthrown him.