I have found some info about hiscores in mame. http://mamedev.org/devwiki/index.php/FAQ:Features#Why_doesn.27t_my_favorite_game_save_my_high_scores.3F
it seems that games that originally supported to save hiscore can also do it in mame but many others games don´t save hiscore. mamedevs also mention -autosave parameter but........ "however, only a subset of MAME's games fully support save states, so this approach is not a perfect solution."
This way I don´t know where hiscore values are saved in hard disk and maybe it can be different for each game so it seem difficult to get the hiscore value for each game and show it in the mala layout.........at least it seems difficult for me with my little knowledge about how mame works.
Also found an other option to save hiscores using the unofficial hiscore.dathttp://highscore.mameworld.info/
this way we create a folder named "hi" in the mame folder and we get a file called "romname.hi" for each saved hiscore. this files are "data", not text, not sure in which format. This approach seems easier as mala could search this folder to get the file .hi for the current rom and show it in the layout. Not sure how this .hi file could be readed.
The bad thing is that hiscore.dat is not supported in official mame releases (I don´t know why) but only supported in other mame modifications as mameplus.
This is the info that I have found about hiscores............ maybe any developer who knows better about how mame and mala works can say if hiscores in mala are possible...........