Biotin/MSM/Castor oil are all good to be used in conjunction with another 'real' hairloss treatment. If you're counting on these alone to work for you for you might be in for a disappointment.
Biotin helped my nails that's for sure, as far as hair growth, it's very hard to say. Some people claim MSM helped their hair a bit. It seems like that the common conscious around is that biotin together with MSM might at least help speed up hair growth, which might be useful for fullheads/girls/beard growers trying to grow their hair/beard out, but as as far as hair loss goes there's not much to it.
I'm currently off treatments and I keep my hair buzzed to 3mm so now it's very easy to apply oil as opposed to when I had longer hair, so I just use a mixture of castor/coconut/jojoba/argan oil, and apply it to the scalp for 2-3 hours. I don't know if this actually helps the actual hairs, but at least my scalp skin looks better now.
Back when I was on treatments (finasteride + minoxdil), I would also take castor oil orally (2-3ml a day), 5mg biotin, and 5grams of MSM powder. My hair was looking quite good back then but I cannot say with any certainty if castor oil/biotin/msm helped with anything really, although my hair was growing pretty fast back then, so it might have helped with that at least.