Madh-e-sahaba is an urdu word, meaning praising sahaba, as of its translation suggests, their is nothing wrong in this, until or unless things are not being exaggerated, but at-least in pakistan these types of conferences are done on days other than maulud-ul-nabi, i.e:12 rabiul awal, so if someone is celebrating birthday of prophet or anyone, than it is separate question is it right or wrong. I believe it is wrong, and its copying of kuffar, which is not allowed.
Now to do this madh-e-sahaba, carrying some special colour flags and coming out in streets on specific day of year for this purpose, it is not the sunnah way, it is not encouraged in islam. Because it hurts people and their daily routines. It blocks the path ways, roads streets etc. SO it is not a good thing, and it is not needed to do so in anyway.
You must ask the people doing so why they do so, and let us know if they can provide some solid references, than we can answer accordingly.