Just a few most occuring ones.  They could ask anything....

why are u going?
who do u have in US ?
when are u coming back ?
DO u have any intention on living, working, or studying in US ?

Who is going to be responsible for the cost of travelling and living while in US ?

When are u coming back ?
Who/what  do u have in Nepal and ties you to the country ?

what is ur son/daughther doing in US ? how long has s/he been there ?
what is ur earning here in Nepal ?
any other countries visited besides India ?

How can the US government be sure that u will leave US once the said trip is completed ?