Cremation?

Strictly it does, but it's never been made clear how strict his mother was in her adherence to the religion; Howard certainly isn't. He was born into the Jewish race but he has, in practice, entirely abandoned Jewish religion - except for the bits of it so ingrained into his upbringing that they've become part of his natural character.

Incidentally, under UK law, no matter what you've written in your will or left as instructions, once you're dead you are not a legal person, your corpse belongs to your next of kin, and only they can decide what happens to said corpse, even if they go directly against your publicly-known intention. If this holds in US law (I have no idea!), then Howard may have simply overridden his mother's wish to be buried. I know of no cases where a next-of-kin has done such a thing - generally speaking your next of kin is someone who cares about you and would WANT to abide by your wishes! - but nothing in our law would prevent them.

I don't think either Howard or his mother was Orthodox. And also, she did not die near where she was going to be buried. They had to ship her. If she was a Reform Jew, then it's no problem. See below:
http://www.myjewishlearning.com/article/judaism-on-cremation/

While cremation was known in the ancient world, the universal Jewish practice until the late 19th century when cremation became popular was to bury the dead in the ground or in mausoleums. In modern times, Reform Judaism has little objection to cremation, although it normally favors burial. Orthodox and, to a very large extent, Conservative Judaism frown severely on cremation. Orthodox Rabbis have been especially virulent in their opposition to the practice.

Probably some forty years ago, my mother received some religious newsletter that discussed cremation. It said that in Biblical times, the Jews would bury and the Gentiles would cremate and then suggested that the trend had reversed that Jews now cremate and Gentiles bury.

I guess that lack of space for burials have necessitated changes in Jewish practices, maybe?