Use the molecular weight calculator at https://www.the-hive.ws/forum/pt.pl?Cat= (https://www.the-hive.ws/forum/pt.pl?Cat=)
to find out the molar weight of your reactants.
Ammonium chloride is NH4Cl, and the calculator will tell you that one mole weighs 53.49g.
Bromosafrole is C10H11O2Br and hence weighs 243.1 g/mole.
So, to use a 10x molar excess, you should use 534.9 grams of NH4Cl for every 243.1g of bromosafrole (assuming that 100% of the NH4Cl will end up in the alcohol, which is not true in practice). The 10x figure is good for methylamine, but as NH4Cl is so cheap, if I were to perform the reaction you are working on, I would use about 20-25x molar excess of NH4Cl. How much that is in grams is left as an exercise to the reader ;)