I am actually an Udu player...I know I know there's one in every crowd.
Anyway I have been recording mine for years and tried every combination you can think of.
Mine is the all clay dual hole non head variety (LP actually).
Although the lp ones have a small hole in them which fits a shure sm-98 perfectly...its sounds too close, metalic and boomy...
My best results ever were with an AT 4060 placed about 2 feet up from the drum while the player is seated on the floor. I find mono actually the best way to record these drums (actually most hand percussion really). It allows a much more focused and tighter sound which you can pan and place in the mix.
Since I am equal parts percussionist and studio engineer I will actually "play to the mic" much like a singer would. The bassy boom comes out of the top "bottle shaped" hole as the side hole is struck. If it is a true vase style udu which traditionally only had the one hole it will have much more of a slap sound.
When I say play to the mic, I will play the higher pitched slap tones with the mic 2 ft away angled at the middle of the drum, I will then control the boom and volume of the bass notes by turning the the mouth of the drum toward the mic as needed... of course this takes practice and understanding on and off axis mic techniques while playing helps.
Ok so assuming your player is not an audio engineer I would consider 3 mic set up choices.
Each choice will be based on where the drum will sit and how important it will be to the mix.
If the drum is the main and central percussion part of the song, as I said a single mono LDC Tube mic works great. The bass is surreal.
If however you are going for a more "traditional" world sounding recording a stereo set of either you favorite LDC's or better yet a set of something like sm-81's or KM 84 / 184s in an x/y pattern about 3-4 ft away will be more even giving a better balanced clay tone (but much less exagerated bass).
Lastly you can also try a combination of LDC over the bass sound hole and a SDC over the players hands by where the neck and the body meet. This will give you a good up close balance of highs and lows.
Of course this is what works for me and your miliage may vary....plus one word of advice...dont drop a mic pre on the udu. I now have a wonderfull decorative re-glued planter thanks to a cheap mic pre falling off of a shelf and onto the drum which I set on the floor while looking for mic shock mounts on said shelf
Good luck...
Paul