The old man who lives just around the corner?
You have to attend his funeral with the family you live with?
And the funeral is in his house? And his body is in his house?
First of all, you should wear a back dress when you attend the funeral. Black dye does exist in the mid 1800s, so you may have to dye a dress for the occasion. If the deceased has a wife who is still living, she will be expected to grieve for at least a year -wearing black clothes for that period - and perhaps a black veil, although some believe this is not a necessity. Crepe is a popular material for a mourning dress - the fabric has no sheen and therefore, no life of its own. During this century, there is even special jewellery created for the mourning period, embellishments to add to an all-black attire. The next stage of mourning for this unfortunate fellow's wife will allow other colours of clothing, perhaps grey or soft blue.
In the home itself, it might seem unusual to you, but you may notice that the clocks have been stopped at the moment of death and all the curtains closed.
Pallbearers will carry the coffin to a waiting horse-drawn carriage. Pallbearers will wear black gloves and hatbands along with a regular dark suit, although previous to 1850 they would have worn black cloaks.
The carriages containing the clergyman and pallbearers will leave the property first. Then will come the pallbearers in a separate carriage, followed closely behind by the carriages of the family.
Once arrived at the church, the coffin will not be opened. Of course, once you are at the church, you will need to be quiet. Any kind of loud talking, especially laughing, will appear very rude.
And now you know.