Undergraduate thesis main author credit and prestige
I am not sure about undergraduate theses, but in graduate school the thesis is almost always (at least formally) an individual effort, and the student's name is the first and only name on the thesis itself. However, when that thesis is revised into a paper for submission to a conference or a journal, it is acceptable to acknowledge one's advisor (and possibly other committee members) as 2nd/3rd/etc. authors. In some cases where an advisor makes a more significant contribution than the student to the revised paper that is being submitted for publication (e.g. time/effort), their name can be first.

For undergraduate theses, I would guess that the students' names should appear first and advisor's name should appear last, if the thesis is not published but merely submitted to the university to fulfill the graduation requirements. However, when that thesis is revised for publication, the same rule as for graduate papers applies - if the advisor actually contributed more, their name can go first. Experienced, well respected faculty with tenure are not concerned with pushing their name, so more often than not they allow students to go ahead of them on the author list.

Finally, having your advisor go first on a revised thesis submitted to a conference or a journal may not be a bad idea, if your names are still on that paper. This still provides you acknowledgement for academic research and publication activity, so I would not worry too much if your name goes first or second or third.

It is an early effort in your research career, which will be superseded by more serious research work that you will do. Rather than straining your relationship with advisor, it may be wise to let it go and instead make sure that you remain on positive terms, as he/she may be writing recommendation letters for you... ;)

Good luck!