A - Thanks for the question! You are correct in assuming that someone was taking the Eucharist to someone who is sick or homebound. Frequently, priests, deacons and even lay extraordinary ministers of Holy Communion will access the tabernacle to get the Eucharist to take to the sick. The little "gold box" you saw is called a pyx.
The Church understands that there are some people who cannot attend Mass due to their physical condition and we certainly don't want to deprive them of the graces they receive in the Eucharist.
Here is what the document entitled "Holy Communion and Worship of the Eucharist outside Mass" in paragraph 20 says on the subject:
The Eucharist for Communion outside a church is to be carried in a pyx or other covered vessel; the vesture of the minister and the manner of carrying the Eucharist should be appropriate and in accord with local circumstances.