There is no legal meaning to 'next of kin'. Anyone can nominate who they like (including complete strangers if they so choose) to be recorded as their 'next of kin' (so that they're contacted if the person is taken ill or dies) but there's absolutely no obligation upon anyone else to take the slightest notice of that nomination. (There are obviously codes of conduct and 'professional duties' which might apply to hospitals and nursing homes, but they're not legal obligations).
Nobody can own the body of a deceased person. If someone steals a dead body they have not committed any crime (other than, possibly, 'preventing a burial').
Similarly, nobody has any specific rights or duties with regard to a dead body. There's never any obligation upon anyone to arrange a funeral but anyone is free to do so. Basically it's 'first come, first served'. A complete stranger can arrange someone's funeral, even if (for example) that means that the person is buried (or cremated) with the rituals of a different religion to their own. (Again, professional codes of conduct might apply. For example, an undertaker and a Catholic priest might well refuse to have any part in the burial of the corpse of a Muslim which they know to have been stolen from a chapel of rest, but there's no absolutely law to prevent them from doing so).
Unless you can persuade the person who is paying for the funeral to change her mind, your 'goodbyes' will have to be at the funeral.
Chris