Bathing the deceased is a collective duty; it ought to be performed by the closest family members if available; otherwise by other members of the community, preferably those who are known for their integrity.

The general rule is that the close male relatives should bathe the male person and the close female relatives should wash the female.

However, an exception is the case of parents and children and spouses.

A son can bathe the mother with his sisters or other close female relatives; likewise, a daughter can wash the father with the help of her brothers, sisters, etc.

It was Ali who bathed his wife Fathimah with the help of Asma bit Umays.

As for the procedure, let me list it as follows:

1- Place the body in a high place: a bench or table

2- Private parts must always remain covered; wear gloves

3- One person should gently raise the head; another person should gently squeeze the tummy to squeeze out the impurities, and a third person should hose down the impurities.

4- When the water runs clear, the body should be laid to rest. The washer (wearing gloves) should wash the private parts from underneath the cover without lifting it;  Then give him/her a wudhu except there is no rinsing, gargling of mouth or nostrils; Just wet some cotton balls and clean the teeth, nose, and ears;

5- Then wash the entire body starting from the head and the right side; turn the body gently to the other side, then bathe left side;

6- Wash at least three times; one may increase the number of washes if needed, but it should end in an odd number of times; in the final rinse, mix some camphor with the water.

7- Once the bathing is completed, wipe the deceased dry with towels and shroud him or her before offering salatul al-janazah.

For a concise guide to all aspects of Islamic funerals, you can access my booklet here in pdf.

http://www.alnoorusa.org/Islamic_funeral_rites_and_practices_booklet.pdf

Almighty Allah knows best.