Jews must be buried before sundown the day following their death. I don't know if they would need much funereal care although there are many Jєωιѕн funeral homes that could deal with her remains privately.
Working at a funeral home I can say that the first sentence above applies only to observant Orthodox Jews. I have no idea how observant or orthodox RBG is about the Jєωιѕн religion. I do know that there are those with cultural Jєωιѕн affiliation who have some elements of Jєωιѕн tradition associated with their final rites (for example, having a
"shomer", the family sitting shiva) but otherwise do not strictly observe what is traditional … i.e. there may be more than 24 hours after death before burial, there may be embalming, there may be cremation, they may be dressed in regular clothes rather than a shroud, they may use a regular wood casket rather than a traditional Jєωιѕн casket. The "funeral care" for a traditional Orthodox Jew is probable as complex, if not more so, than that for any traditional funeral. Just for the FYI
An Overview Guide to Handling Jєωιѕн Dead.
There are indeed Jєωιѕн funeral homes in major cities (not where I live) who exclusively handle Jєωιѕн funerals, and observant (or not) Jews would likely engage these firms rather than an Irish or Italian undertaker. Any and all funeral homes will deal "privately" with a family. I can't speak to DC, MD, or VA regulation, but in Washington state every death is a matter of public record and every funeral home is required to submit a death notice to the local newspaper for publication (no charge to the family for this, and this is distinct from a published obituary).
It is certain that there are those who would not want President Trump to have the opportunity to appoint another justice to the Supreme Court, this would actually be true in any administration, the "other side" never wanting to see this. Yet, "motive" alone does not provide sufficient evidence that RGB is dead and an imposter is standing in for her.