Every hummingbird mom is a single mother. Male hummingbirds provide no care to their offspring. In fact, after they mate with the female, they simply move on and may never see her again.
However, hummingbird females make do. Most build their nests from all sorts of odds and ends, like moss and lichens and grass and even lint from a dryer for clothing, and then bind it all together with spider webs. These nests are very hard to find.
Incubation--which is done only by the female--usually lasts 16-18 days, sometimes longer during cool weather. She typically lays one egg, skips a day, and then lays a second; incubation does not start until both eggs are laid. There are almost always two eggs; if only one were laid, the female would be maximizing her reproductive potential; if three or more were laid, it's likely the female would not be able to provide sufficient food for the nestlings and all would die.