My money is on potatoes, for the following reasons:
- They are sturdy plants with a good output. From Wikipedia:
According to conservative estimates, the introduction of the potato was responsible for a quarter of the growth in Old World population and urbanization between 1700 and 1900. In the Altiplano, potatoes provided the principal energy source for the Inca civilization, its predecessors, and its Spanish successor. Following the Spanish conquest of the Inca Empire, the Spanish introduced the potato to Europe in the second half of the 16th century, part of the Columbian exchange. The staple was subsequently conveyed by European mariners to territories and ports throughout the world. The potato was slow to be adopted by European farmers, but soon enough it became an important food staple and field crop that played a major role in the European 19th century population boom.
They are nutritious. Wikipedia also compares it to other staple foods, and while they not the ones with the most of any given nutrient per portion, they do have a relatively good amount of vitamin C while being comparatively low on carbs and fats (as in they have less carbs per weight than rice, but please notice they are still really high in carbs anyway).
They are DELICIOUS[citation needed]. You can boil'em, mash'em, stick'em in a stew. They are also very good in french fries format, which is healthy because cooking does not kill all germs (to be really healthy, take this with a grain of salt).
While potatoes are really good, don't rely just on them. Ireland learned this the hard way once due to a potato blight.
Also, to really meet their nutrition requirements in the long run, your people will need to vary the plants they eat. A house may not provide adequate environment for maize (corn), wheat and specially soy and rice. They will need some fields for those.
There is a novel called The Martian, which was also made into a movie starring Matt Damon. It is about an astronaut/botanist stranded in Mars, surviving alone on a diet mostly based on potato. The book aims to be as scientifically correct as possible and is really pedantic about every tiny scientific detail. The rocket science and chemistry in the novel are precise and correct, but the fact that the protagonist survived for months on potatoes alone is the one thing that is off in that book.