Hi, Anita, and welcome to EmpowHer! Thanks so much for your question.
You are a wonderful friend to want to help your friends conceive a baby.
There are a lot of causes of male infertility, and low sperm count is just one of them. If your friend's husband has 0 sperm count, it sounds like he has a blockage of some sort. Is he seeing a urologist? Are they considering surgery or other treatment?
Men with zero sperm count have a condition called azoospermia. Here is some information on this from the Cornell Institute for Reproductive Medicine:
"Men with zero sperm count can be divided into two broad groups: (1) men who have an obstruction problem or blockage, meaning they are making sperm, but the sperm can't get out, or (2) men who have a production problem, meaning they are not making sperm, a condition called "non-obstructive " azoospermia.
"We can easily determine which group an infertile male is in by doing a testicular biopsy, also using a microscope to minimize discomfort and complications.
"Blockage can also be caused by a urinary tract infection or by the sexually transmitted diseases chlamydia and gonorrhea. Bacteria can infect the tiny duct called the "epididymis," which is essentially a swimming school for sperm before they are able to swim to fertilize an egg. Infection of the epididymis can cause scarring and blockage, inhibiting the sperm from leaving the duct to fertilize an egg. With the use of microscopes employing 30-power magnification, blockage repair success rates are extremely high."
Here is that page if you would like to read more of it:
You also asked specifically about homeopathy, yoga, ayurveda, sleep and nutrition. Here is an ayurvedic medicine page that talks about low sperm count and its causes:
And here is some advice on yoga poses:
And on diet:
Have your friends been to see a fertility specialist, a urologist or a homeopathic doctor?