My father, non-US citizen, non-resident alien, passed away overseas, and had exceeding 15k to give me. Which way is better? - 1) transferring money from his account(overseas) to mom's account (overseas, mom is alive), then from mom's account to my account in USA as a gift; OR transferring from dad's account to mine as inheritance (provide Death Certificate), then close dad's account? Thanks

Transfer the money from father's account to your account as an inheritance is the best way to handle this.

There are no estate or inhieritance taxes due at the federal level, and probably no inheritance tax at the state level (though that depends on the state in which you live).

Sorry, AtlantaTaxExpert, I miss-typed the figure, which should be 150k, does it change your answer? Thank you.

The amount is irrelevant, because the inheritance is NOT subject to U.S. taxes.