What should my friend do, who secretly converted to Islam and refused to marry a Christian man, while her family is forcing her into this marriage, and she does not have the money to move away nor can she find anyone to support her?

A Muslim woman is not permitted to marry a non-Muslim. She must refuse him and threaten her family with leaving the house if they insist. She must declare her Islam openly at the appropriate time and seek a Muslim husband, seeking assistance from her friends or charitable people. If she is able to marry a Muslim man to free herself from the complications of marrying a non-Muslim, then that is good. Her marriage contract should be officiated by a Muslim judge, or their community, or a man who marries her, as clarified in previous fatwas. Her disbelieving guardian should not officiate her marriage contract.