What should the questioner do about her hesitation to advise her neighbors regarding their watching of TV series that contain prohibitions, and is her action of staying away from them and lowering her voice correct? And what are the consequences of abandoning the prohibition of evil?

Indeed, forbidding evil is a communal obligation (fard kifaya), and it may become an individual obligation. Abandoning it when it becomes an individual obligation is forbidden and carries a severe warning. Imam Ahmad and Ibn Hibban narrated from Abu Bakr (may Allah be pleased with him) that the Prophet (peace be blessings be upon him) said: "If people see an evil and do not change it, Allah is about to encompass them all with His punishment." Ahmad and Ibn Majah narrated from Abu Sa'id al-Khudri that the Messenger of Allah (peace and blessings be upon him) said: "Let none of you belittle himself. If he sees a matter regarding which Allah has a say, let him not refrain from speaking about it. For if he meets Allah having neglected that, He will say: 'What prevented you?' And he will say: 'I feared people.' Then He will say: 'I was more deserving of being feared.'" Some scholars have considered neglecting to forbid evil among the major sins. Merely asking to lower the volume is not enough; rather, it is necessary to forbid watching television series and clarify their unlawfulness according to Sharia, based on the Prophet's (peace and blessings be upon him) saying: "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; if he cannot, then with his heart—and that is the weakest of faith." Shyness that prevents one from forbidding evil is a blameworthy weakness in Sharia, and it is not among the praiseworthy forms of modesty.