What do we call the person who gives a beggar money? [closed]

"Benefactor" appears to be the most likely term.

(OALD) a person who gives money or other help to a person or an organization such as a school or charity
♦ a generous benefactor
♦ The equipment was funded by friends and benefactors of the hospital.

Additions in view of delimiting better the scope of the term "benefactor", delimiting that the comments to the present question suggest (user DhruboZ)

It is true that "benefactor" is a term that applies to acts of giving of several sorts, not just the act of giving alms, which concerns specifically enough beggars and certain cases of persons in dire need. Nevertheless, it does apply to beggary.

• These are thy sports, Fortune! to elevate the beggar; to deride his benefactor. (The Beggar and His Benefactor, 1809)

It seems to me that it matters not at all whether the act of alms giving is occasional or regular and whether or not regularly repeated for the same beggar (not so rarely, this is the case).

Further, there is a question of idiomaticity that could be looked at. If one were to refer to such a person who gives alms as they stand in relation to the receiver, it wouldn't be as idiomatic to use phrases such as "my almsgiver", "his almsgivers"; "almsgiver" is, by the way, a term that makes abstaction of the idea of goodness that characterizes the act, a more neutral term, that nonetheless can have a place in the present context; "my benefactor", "his benefactors" would be more natural. There is a certain certitude of this fact to be gained in the information provided by the following ngrams.

(my benefactor,my almsgiver)
(my benefactors,my almsgivers)
(his benefactor,his almsgiver)
(his benefactors,his almsgivers)
(their benefactors,their almsgivers)

It can be remarked from the third reference in the five preceding ones and from this page that there exists a usage of the possessive "his" for "almsgiver", but it is rare in comparison with the usage with "benefactor" and it is of quite recent origin (very rare in the past). This tends to show that no substantial usage for this type of phrase exists that would be on the point of beginning to displace the traditional one.

"almsgiver" is specific for the situation you describe.

• almsgiver - a person who gives alms.
• alms - something (such as money or food) given freely to relieve the poor.
  e.g. distributing alms to the needy