Do you have to follow a monastic lifestyle to attain enlightenment? How do the different groups/sects of Buddhism view attaining enlightenment and living a common life? In other words, do they think it is possible to be a common person and achieve enlightenment? Even for someone who has a family, friends and coworkers that aren't Buddhists?
Do you have to follow a monastic lifestyle to attain enlightenment? At first approximation, the answer is: yes in Theravada, no in Mahayana.

Since probably as early as Milindapanha (~100 BCE) and most certainly by the time of Vissudhimagga (~430CE), the orthodox (~Theravada) position was, you must be a monk to attain Nirvana.

But since you asked about Enlightenment, I should point out that Enlightenment is the goal of Mahayana, while in Theravada, the final goal is usually called Nirvana (Nibbana in Pali), not Enlightenment (Bodhi in Pali). In Mahayana, Enlightenment can be attained by a layperson.

These are "official" positions (as much as we can talk about official positions in such a heterogeneous conglomerate of teachings as Buddhism). Informally, in my own understanding, what some Mahayana schools call "Enlightenment" is what Theravada schools call mere "stream-entry". Other Mahayana schools however have this notion of multiple levels (bhumi), in which what Theravada calls "stream-entry" is level 1 of 10, with Final Enlightenment counted as 11th. It kinda gets complicated from "stream-entry" onward, because the boundaries of "self" no longer apply, so it is difficult to talk about Enlightenment with no subject to tie it to.

Anyway, from practical perspective, the point is, it is extremely difficult to make any meaningful progress towards Enlightenment/Nirvana if most of your focus is on pursuing material ends (success, wealth, entertainment, helping your relatives achieve the same). In order to get pretty close to X while leading a semi-normal life, one's top priority must be spiritual practice, followed by family and everything else. This basically means, squeezing study of Buddhist philosophy here and there, making meditation part of your daily routine, and, most importantly, deliberately utilizing your family &amp; work situations as shootingrange for Dharma practice.