Is it permissible for a woman aged 56 to seek a husband who will care for and protect her?

There is no harm for an elderly woman to seek a righteous husband, for old age is not a legal impediment to marriage. The noble verse: "And marry the unmarried among you and the righteous among your male servants and female servants. If they should be poor, Allah will enrich them from His bounty, and Allah is all-Encompassing and all-Knowing" (An-Nur: 32) is general and not restricted to a specific age. An elderly woman may need a man to care for and protect her.