I was taught that Sn/HCl should be used for reduction of nitrobenzene to aniline. Can I ask if there are any alternative reducing agents (for example, LiAlH4?) to do the same task?
Hydrogenation of aromatic nitro groups (over, for example, Pd/C) usually results in reduction to the corresponding aniline and is probably easier to carry out and work up as compared to Sn/HCl.
Wikipedia has a list of several conditions for reduction of ArNO2 to ArNH2: https://en.wikipedia.org/wiki/Reduction_of_nitro_compounds#Aromatic_nitro_compounds It also states that LiAlH4 reduces it to the azo compound ArN=NAr, which is corroborated by March's Advanced Organic Chemistry (7th ed.).
In any case, from a practical perspective, you would probably want to avoid using LiAlH4 if there's a simpler alternative. It's dangerous and the workup is not fun.