While my friends sleeps he foams at the mouth and freezes. Could this be nocturnal epilepsy?

Does not sound norma. That is certainly a possiblity and there are other "parasomnias" that can cause this behavior. This is easily clarified with a sleep study which a primary care doctor can arrange. During a sleep study brain waves and patterns are measured and epileptic behavior would likely be detected. It would also be noteworthy to keep a log before any appointment as to how he feels after sleeping like that.
Nocturnal Epilepsy. Yes. Have him see a neurologist. If they check an EEG they may not notice a problem esp if he is awaken during the testing. In my practice when I am concerned that my patient has seizures in sleep I strongly consider an overnight EEG - can be in hospital or at home. Unfortunately, at home overnight EEGs (AEEG) are not available everywhere. .
Need neuro eval. Recording his sleep with eeg would be the answer. If one of these events can be caught on the eeg, it would answer whether they are seizures. They could be sleep related events of an non-epileptic nature. Have him get a thorough medical evaluation and recommend a referral for neurological evaluation.