What kind of bussines is 'antifragile' during these times?

An antifragile business should be antifragile period, not just in certain times. N.N. Taleb would surely give you a vigorous public thrashing for mis-applying his term :-).

Most online services will grow while people are stuck at home. Entertainment will grow somewhat, but practical and educational services will grow even more.

As well as a huge immediate demand for masks & sanitizer, the public will probably demand an substantial stockpile of such supplies for the future. So if you build a mask factory, you don't have to worry that demand will fall off a cliff in a few months.

Playset makers probably. I'm considering buying one to keep my kid engaged. They can't share with the neighbors.

Utilities, staple goods, healthcare. People still need to cover the basics even if they're not going to work.