Your friend needs to stop making excuses and get an evaluation. At 24 months, the expectations of what he should be able to communicate are strikingly different than before the 24 month mark, so now is a good time to get a referral for an evaluation from her pediatrician and get an appointment for it set up right after his 24 month birthday. Tell her to get the papers they have her fill out in advance, and work on them at home. They will ask what words he can say or tries to say, and other questions. It is MUCH easier to do this at home when she can think about things easier, plus she will have more time with the therapist.
I highly recommend that she consults a group to assess her son. Like her son, mine only had a few words at that age. He tried, but only had vowel sounds - no consonants. 3 people assessed him at the same time - a team approach. I will be forever grateful to them, because they gave me excellent advice and found me a speech therapist who was good for him at the beginning of his speech work. She was young, energetic, and pretty. He LIKED her. She also knew how to get him to continue when he got mad at having to do it.
I used another lady later, when we moved, one with many years of experience because he had a speech problem that needed more experience, but that was okay. I will ALWAYS appreciate my son's first speech therapist.
Tell your friend that it is much easier to help a child at 2 than it is later. Offer to go with her. Whatever you can do to get her to listen, articles, etc.
Good luck!
Dawn