Answer: The Shulchan Aruch (OC 263:8) writes that as there is a machlokes as to whether two families who are lighting candles in the same house should both recite the beracha upon lighting, only one family should recite the beracha, following the rule of safek berachos lehakel, we are lenient with regards to doubts about berachos.
Likewise, the Shulchan Aruch Harav (OC 263:15) writes that unless the guests have their own room to light in, there is no requirement for them to light their own candles. Thus, they would not be able to recite the beracha (See Aruch Hashulchan OC 263:5).
The Rema, however, disagrees, writing that the ashkenazi custom is for each person to recite the beracha upon lighting. The Magen Avraham (263:15) and Mishna Berura (263:35) explain that each person adds extra light with their candles (See Shulchan Shlomo, Shabbos 263:n12).
R’ Yitzchak Yaakov Weiss (Minchas Yitzchak 10:20:1) writes that as there is a machlokes as to whether guests should light their own candles, they should ideally light before their hosts. This way, they can say a beracha when lighting the first lights. As there is no dispute about the hosts lighting, they recite the beracha upon lighting the extra lights (See Rivevos Ephraim 6:283).
While sefardim typically follow the Shulchan Aruch, there is a machlokes as to whether guests should recite their own beracha. The Kaf Hachaim (OC 263:54) writes that the minhag of sefardim is for everyone to recite the beracha.
However, the Ben Ish Chai (Noach 2:11) and R’ Benzion Abba Shaul (Ohr Letzion 2:18:6) only allow guests to light with a beracha if they do so in their own room.
In conclusion, the minhag among ashkenazim is for guests to light candles with a beracha, while some sefardim are particular to light in their own room. Ideally, the guests should light first.