If both mother and father ask for food and clothing, whom should I give them to first? I heard that mother should be cared first but anyone else knows?
If you are paying for the food or drink,
it is not the obligation to honor your parents but giving charity, in which case the woman comes first.
(But I guess if they are married you can give the father and he will give his wife.)
But if it belongs to your parents then, if your parents are married, you need to give your father first (some people say that this is true specifically of drinks, which is the job of the wife to give the husband),
but, if they are not married, legally you can give to whichever you want Yoreh_De'ah.240.14
(But I heard that we should give preference to woman in everything except saving life, so if legally there is not preference you should give your mother.)