So after waiting a while, I was able to come up with an answer to #1 but #2 is still questionable.
For part a I was able to come up with with the 3 equations:
2HCl + MgO
MgCl
2 + water
Mg(OH)
2 + 2HCl
MgCl
2 + 2water
Al(OH)
3 + 3HCl
AlCl
3 + 3water
After this part, I have trouble finding the greatest amount of .1 M HCl per gram. I first look at the ratios between the acid and the antacid. I find the ratios (1:2) (1:2) (1:3). From this result I'm looking at the Aluminum hydroxide as the answer. I read further into the question and says," ... greatest amount of .1 M HCl per gram." At this point I don't know what equation to use. I'm not sure if the .1 M HCl is redundant or not, or if I put the moles of HCl over each equations' respective masses of the antacids to find an answer.