Is it permissible to take out an interest-bearing loan to purchase a plot of land in order to protect a paid deposit and avoid losing the land, given the unavailability of Islamic alternatives and the family's need?

Usury is one of the gravest sins, and Allah has threatened war against those who commit it. The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes it, the one who feeds it, its scribe, and its two witnesses. A single dirham of usury is more severe in the sight of Allah than thirty-six acts of fornication. Necessity does not permit usury, only dire exigency, such as one on the verge of perishing who finds no sustenance except through usury. This dire exigency does not apply to your situation, as there is a permissible alternative, such as renting, even if it is costly. One should be patient and await Allah's relief, for Allah has made piety a means of provision. A person should reflect before embarking on purchasing something for which they do not possess the price.