Minimum Number of Sheets for Shrouding
Question

What is the acceptable minimum number of pieces of cloth for shrouding a man or a woman?
Praise be to Allah.How to shroud a dead Muslim
It is best for the deceased to be shrouded in three pieces of cloth if it is a man and five if it is a woman . 
Minimum shrouding of men and women in Islam 
The minimum number of sheets in which the deceased may be shrouded, which fulfills the obligatory duty, is a single piece of cloth that covers the entire body. This is the view of Abu Hanifah and Ahmad, and is one of the two views held by the Malikis. (See: Hashiyat Ibn `Abidin, 3/98; Al-Mughni, 3/386; Mawahib Al-Jalil, 2/266) 
They quoted as evidence for that the Hadith narrated by Al-Bukhari (4047) and Muslim (940) from Khabbab ibn Al-Aratt (may Allah be pleased with him) who said: When Mus`ab ibn `Umayr was killed on the day of Uhud, he left nothing but one sheet. If we covered his head with it, his feet became exposed and if we covered his feet with it his head became exposed. The Prophet (peace and blessings of Allah be upon him) said to us: “Cover his head with it and put Idhkhir (a kind of grass) over his feet.” 
Al-Zayla`i (may Allah have mercy on him) said: “This indicates that covering the `Awrah alone is not sufficient.” (Hashiyat Ibn `Abidin, 3/98) 
Shaykh Ibn Baz (may Allah have mercy on him) said: 
“If the deceased is shrouded in a single sheet, that is permissible, whether it is a man or a woman. The matter is broad in scope." (Majmu` Fatawa Ibn Baz, 13/127 )
Al-Bassam (may Allah have mercy on him) said in Tawdih Al-Ahkam (2/39): “What is required for the deceased in all cases, whether young or old, male or female, is a single sheet that will cover the entire body of the deceased.”
The view of Al-Shafi`i  (may Allah have mercy on him) is that the minimum shroud is that which covers the `Awrah, and for a woman a sheet that will cover all of her body except the face and hands. This is the other view held by the Malikis. (See: Al-Majmu`, 5/162; Mawahib Al-Jalil, 2/266). They also quoted the hadith of Mus`ab as evidence. 
An-Nawawi  (may Allah have mercy on him) said: “If covering the body was obligatory, they would have bought a shroud with what he left behind (his weapons etc), and if he did not have any wealth, the shroud would have had to be completed from the Bayt Al-mal, and if there was none such, then the Muslims would have had to pay for it." (Al-Majmu`, 5/150-151)
The response to this is that the Prophet (peace and blessings of Allah be upon him) and his companions did not have anything with which to shroud the martyrs of Uhud , and they even shrouded two men in one cloth, as was narrated by Al-Bukhari from Jabir ibn `Abdullah (may Allah be pleased with him) who said: The Prophet (peace and blessings of Allah be upon him) put two men from among those slain at Uhud in a single cloth, then he would say: “Which of them had memorized more Quran?” and if one of them was pointed out to him, he would put him in the Lahd first. 
Where would they buy the shrouds if they did not have anything with which to shroud the martyrs of Uhud? 
If no proper shroud is available, and there is not enough to cover the entire body, then his head and part of his body should be covered and whatever is left exposed should be covered with Idhkhir or some other kind of plant. That is because the Prophet (peace and blessings of Allah be upon him) said, in the story of Mus`ab ibn `Umayr  (may Allah be pleased with him) : “Cover his head with it and put Idhkhir (a kind of grass) over his feet.” (Al-Bukhari and Muslim) 
Shaykh Ibn `Uthaymeen  (may Allah have mercy on him) said in Al-Sharh Al-Mumti` (5/225): “The evidence that this (i.e., covering the entire body of the deceased with the shroud) is obligatory is the fact that when the Companions did not have sufficient shrouds, the Prophet (peace and blessings of Allah be upon him) ordered them to put the shroud over the head and to cover the feet with Idhkhir which is a kind of plant. 
If there is nothing available, such as if his garments have been burned and there is nothing with which to shroud him, then he should be shrouded with grass and the like, which should be placed on his body and then wrapped. If nothing at all is available then he should be buried as he is, because of the general meaning of the words of Allah (interpretation of the meaning): 
“So keep your duty to Allah and fear Him as much as you can.” [At-Taghabun 64:16]
For more details, please see the following answers: 154750 , 201085 , 48959 , and 39201 .
And Allah knows best.