Take TOEFL exam to mention it in Resume?!

I don't think TOEFL is such an important exam that you can include it in your resume.

Of course, if some organization requires proof of your English proficiency, then you must include your score in some certified English language testing exam. And there are many well recognized ones at that, the most recognized being TOEFL and IELTS. So, in my opinion, a TOEFL score, however good it might be, doesn't necessarily make your resume any more impressive.

About the improving her English part, I'm sure there are many better (and also cheaper) ways to do that. TOEFL costs around INR 7000, and unless you are required to submit TOEFL scores for any reason, it's not a good idea to do it simply. You can buy a lot of good books on any aspect of English, maybe join a good coaching class or something, with that money. And after all this, I might also add that TOEFL is not all that difficult, having given it myself and got a decent score, without preparation of any kind. 😀

I agree!

I think the interviewer will come to know about how fluent is the interviewee in (any) language during the interview process. So the certificate does no good.
Basically she needs an Aim. So I told her she can keep the Aim in her mind and prepare for a month and then check her progress by taking online MOCK tests. If she feels she has improved her English, well and good; she can now forget about the TOEFL exam. 😁 If not, then give it more time and practice.

To improve English it isn't required to take TOEFL test, else she can practice by downloading software like Eyespeak from those products official sites. In my opinion, writing TOEFL won't improve her communication ability a bit. In fact, if she feels like that it won't last much too long either because anything can only be achieved with practice (which can be) when done regularly without paying as much as 7000 INR. I suggest her to concentrate on her vocabulary and writing (some content) articles through MS Word will also help to improve her grammar and hence she can achieve herobjectives.

Note: For the above mentioned objectives, it isn't required to take TOEFL test unless she has to submit them, because it is costly to attempt.

Here's a general rule of thumb about the things you should mention in your resume: If questioned, you should be able to justify it!