How can the problem of devotional humility (khushu') in acts of worship and reading the Qur'an, and weeping out of fear of Allah, only when alone, be remedied, given the inability to do so in the presence of family or others?

The basic principle for a Muslim is to conceal their good deeds. Whatever one is able to do secretly, they should not reveal to people. Nevertheless, one should not abandon good deeds for fear of people finding out. Rather, a Muslim should obey Allah in all circumstances. If people praise your good deed, this is an immediate glad tiding for the believer, and it does not harm your deed. Seek Allah's help in this and strive against yourself until you become accustomed to doing good in front of people.