In the United States and most Western countries a surviving spouse has the legal right to make decisions as the next of kin. In the Unites States and most Western countries when a parent dies leaving no surviving spouse, all his children are his next of kin.
As for inheritance, you must check the laws of intestacy for your jurisdiction to determine who inherits. It varies in different jurisdictions. Most pass the decedent's property to the surviving spouse. Some jurisdictions also provide a share to surviving children. You can check the laws in your state at the related question link below.
The next of kin would usually be the son. However, a person is able to designate any one to act as next of kin. Also, if the next of kin was a minor, then any responsibility to act as a next of kin, say a medical emergency, should be passed to the adult.
The question is worded very poorly. Who is being referred to? A business partner or a "live together" type of partner?
In either case the answer is probably, neither. You can check the laws of intestacy for your particular state. Heirs-at-law are determined by blood, legal adoption and surviving legally wedded spouse.
Answer 1
Husband
Answer 2
In most countries there is no set "next of kin". In the United Kingdom you have the right to assign your own next of kin, this could be a blood relative or a relative by marriage. If you have neither, you're permitted to assign a friend as a step-in next of kin.
Both your parents are your next-of-kin. However, if you are a minor and one parent has legal custody, that parent has the authority to make decisions regarding your medical treatment.
Your son would be next of kin in a choice between son and sister.
sister
sibling
Mother, if you mean wife of the deceased husband.
The son.
If you are speaking of the relative or relatives entitled to share in your property if you die intestate (without a will) then if you are unmarried your parents are your next of kin. If they were deceased then your sister would be your next of kin. In another sense they are all your next of kin. See related question link.
The step son has no relationship to the aunt. So technically the niece would be the next of kin.
next of kin would be eldest child
The nephews and nieces have equal standing under the law. However, if one wishes to speak of royal precedent, then the deceased's eldest sister's eldest son, and if she had no son, then the eldest son of the oldest sister who did have sons.
Generally, the grandchildren would be the next of kin. You can check state laws of intestacy at the related question below.
Fitness depends on the individual, not a relationship. Next of kin, however, is usually a common way of saying "closest surviving relative" If the deceased was married, the surviving spouse is the closest relative. After the spouse usually come children, then siblings, then parents, then cousins.
A son-in-law is not considered a next of kin in the legal sense. Next of kin typically refers to a person's closest living blood relatives, such as a spouse, children, parents, or siblings. However, the relationship with a son-in-law can still be important in familial matters.
If a person who has no spouse or children dies the living parent(s) would be the next of kin for purposes of inheritance. You can check your state laws of intestacy at the related question link below.
The children of an unmarried decedent are his legal next of kin. You can check the laws of intestacy in the UK at the link provided below. On the first page look for the link at the bottom that will open a chart.
The son would be the inheritor of the remains of the estate in all the rules if succession that I have ever seen.