Project guide asks for authorship without any contributions – how to proceed?
Let’s start with what is going wrong here:


Requiring you to publish something peer-reviewed on the level of coursework is at least dubious. For more details, see Is it ethical for departments to have publication requirements for students
Putting somebody as an author of a paper who made no contribution at all goes against all standards of academic authorship. However, violating this is so common in some countries and fields that many professors may not even be aware of it.
The project guide is abusing her power when she pushes you into giving somebody authorship (who doesn’t deserve it).
If your institution via rules or coercion makes you give somebody authorship (who doesn’t deserve it), this is also an abuse of power.


Now, you have to evaluate the situation to pick your enemies and allies, if any:


If the curriculum has any written rules that you should make somebody a co-author, you can fight those rules – if any professors or a higher power cares about this. In my country, I don’t see much of a problem of turning this into a public scandal, but yours is probably different.
If there are no written rules about authorship, and one of the other professors evaluating your project or a dean of students or similar are trustworthy, you can present the situation to them and try getting them onto your side. At the very least, you may score some points if you can provide evidence that your project guide did not tell you about any authorship aspirations or rules earlier and also did not do her job properly.
The journal (if reputable) will not be very happy if not completely refusing to change authorship retroactively. You could find an ally here (just tell them what happened), but whether the journal has sufficient power over your department is hard to say.
It could sadly be that your institution is full of power-abusing professors and in a position that allows them do this. In this case, the only thing you can do about it is to leave.