Is it permissible for an engineer's wife to remove her niqab in the Netherlands to avert harm and avoid looks of astonishment and fear, and to facilitate her daughter's integration into school, knowing that they are committed to the hijab and Islamic dress?

Your wife is not permitted to remove her niqab for the reasons you mentioned, because it is an obligatory فرض (fardh) according to the most authoritative scholarly opinions. Removing it will not avert harm from her from those people, as the animosity of disbelievers towards Muslims does not depend on the niqab. Furthermore, preserving one's religion is the greatest objective for a Muslim. If studying in a land of disbelief will lead to abandoning some of the sacred laws of religion, then it is advisable to leave it and seek another place in a Muslim country. However, if it is possible to avoid trials (fitan) and the conditions for travel are met, there is no objection to traveling to complete studies. If it is highly probable that the niqab will bring harm to your wife, then there is no objection to removing it to avert harm, while minimizing her going out into the street as much as possible. As for using the verse to justify removing the niqab, it is misplaced, for the verse guides believing women to modesty and hijab so that they may be distinguished from immoral women, and thus those with sickness in their hearts will not covet them.