(a) passed laws that made anti-Semitic acts illegal.
(b) relaxed their immigration policies.
(c) stopped the immigration of German and Austrian Jews.
(d) created the State of Israel.
b would have helped, but unless they had let in all the Roma and 9 million Jews, there would still have been Jews left in Europe to kill (not to mention the homosexuals and other targeted groups).None of them though a) if it's the only option you have
Antisemitism wasn't illegal and neither was racism but making the acts illegal would not have stopped Germany acting of it's own accord.
Relaxing immigration would have been pointless as most never had a passport anyway and would have caused influx of many non-Jews too.
Immigration was not as strictly controlled as it is today and many wealthy Jews who had the means to flee did so and claimed asylum.
There was no Balfour Agreement in effect so Israel was not possible.