How to Look after Graves in Islam
Question

One of my relatives asked the rest of his siblings to donate some money to take care of their mother’s grave, on which a large amount of dust has accumulated, and around it there are many small bushes. This grave is surrounded with an iron railing; it is coated with white paint and her name, date of birth and so on are written on it. Is it permissible for them to give this money so that they can take care of the grave?
Praise be to Allah.Graves are given a great deal of respect in Islamic teachings, and it is not permissible for anyone to mistreat them or tamper with them, to the extent that the Prophet (blessings and peace of Allah be upon him) emphatically prohibited sitting on graves.
Abu Hurayrah (may Allah be pleased with him) narrated that the Messenger of Allah (blessings and peace of Allah be upon him) said: “If one of you were to sit on an ember which burned his garment and reached his skin, that would be better for him than sitting on a grave.” (Narrated by Muslim, 971)
This respect dictates that the Muslims should take care of graves to the extent that will maintain the dignity of the dead and prevent the graves from being exposed to tampering and disrespect.
Permissible ways of looking after graves
That is done by the following means:

Placing a marker at the head of the grave , as the Prophet (blessings and peace of Allah be upon him) placed a marker on the grave of the great Companions `Uthman ibn Madh`un (may Allah be pleased with him), as was narrated by Abu Dawud (3206).

An-Nawawi (may Allah have mercy on him) said:
“The Sunnah is to place an upright marker of stone, wood or other material, at the head of the grave. This was stated by Ash-Shafi`i, Ash-Shirazi and all our companions.” (Al-Majmu`, 5/256)

Making the grave as high as a hand span only, and no more. This is how the grave of the Messenger of Allah (blessings and peace of Allah be upon him) was.

Ibn Qudamah (may Allah have mercy on him) said:
“The grave should be made as high as a hand span above the ground in order that it may be known that it is a grave, so that people will avoid walking on it and will pray for mercy for its occupant […] It is not recommended to make the grave any higher than a small amount.” (Al-Mughni,  2/190)
It is stated in Al-Mawsu`ah Al-Fiqhiyyah (11/342) that the jurists unanimously agreed on that.

The entire graveyard should be surrounded with a wall that will protect it and distinguish it from the surrounding area, and will protect it from any tampering by little children and animals who may mistreat the graves. (See: Fatawa Ash-Shaykh Muhammad ibn Ibrahim, 3/211-212; Ahkam Al-Maqabir by As-Suhaybani, 457)

Prohibited ways of looking after graves
With regard to prohibited means that some people use to protect the graves of their relatives, they are many and vary according to circumstances and environment. They include the following:

Making the grave more than a hand span above ground level. The prohibition on doing that is based on the fact that the Prophet (blessings and peace of Allah be upon him) said to `Ali ibn Abu Talib (may Allah be pleased with him): “Do not leave any image without erasing it or any high grave without levelling it.” (Narrated by Muslim, 969)
Building structures over graves, no matter what type of structure it is, and whether it is high or not, in the shape of a dome or shrine or any other form.

It says in Al-Mawsu`ah Al-Fiqhiyyah (32/250):
“The Malikis, Shafi`is and Hanbalis are of the view that it is disliked to build structures over graves in general, because of the Hadith of Jabir (may Allah be pleased with him): ‘The Messenger of Allah (blessings and peace of Allah be upon him) forbade plastering graves and building structures over them.’ That applies whether the structure is a dome or a room or anything else. The Hanafis said: It is prohibited even if that is done for the purpose of adornment, and it is disliked even if it is to make it look tidy after burial.”

Coating the grave with paint, plaster or any other type of adornment.

It says in Al-Mawsu`ah Al-Fiqhiyyah (32/250):
“The jurists unanimously agreed that it is disliked to plaster graves, because of the report narrated by Jabir (may Allah be pleased with him): ‘The Messenger of Allah (blessings and peace of Allah be upon him) forbade plastering graves, sitting on them, and building structures over them.’ Al-Mahalli (may Allah have mercy on him) said: Plastering means whitening it with plaster, which is like whitewashing. `Umayrah (may Allah have mercy on him) said: The reason for this prohibition is that this is a kind of adornment, and is also wasting money on something that is not prescribed in Islamic teaching.”

Surrounding the grave with a fence, whether it is a fence to protect the grave from tampering and mistreatment, or a wall that is akin to building a structure over the grave, which is prohibited.

Shaykh Al-Albani (may Allah have mercy on him) said:
“Surrounding the grave with this fence in this decorative manner is another type of evil which prompts people to disobey Allah and His Messenger (blessings and peace of Allah be upon him), and to venerate the occupant of the grave in a manner that is not permissible according to Islamic teachings, which is something that is often seen and is well known.” (Tahdhir Al-Sajid  p. 89)

Writing on the grave, whether it is words of praise or eulogy and the like, which comes under the heading of wailing for the deceased or opens the door to veneration and exaggeration about him.
Planting trees on the grave , or planting greenery on it . This is not a custom of the Muslims regarding their graves; rather it is one of the customs of the Christians .

Based on the above, the Islamically prescribed manner of protecting graves hardly needs any money to be spent on it, so long as the grave is protected from mistreatment and tampering. As for painting it or raising it or building structures over it, all of these are ways of looking after graves that are prohibited. The same applies to surrounding it with an iron railing. The fact that there is dust on the grave does not mean that the grave is being mistreated; rather this is something that happens to all graves, because their occupants are buried under the dust and soil.
And Allah knows best.