Guinea pigs are group animals and not wired to be on there own. There are countries where it is even illegal to sell single/rehome single guinea pigs, like Switzerland! Please point out to your mum that a piggy is general happier and therefore healthier if it has company. Two piggies don't cost much more than a single one and do not need much more space either (single piggies need in efffect nearly as much space as a couple, so they can have a good run and a popcorn to keep them healthy)!
We have excellent guinea pig rescues in this country that bond/rebond boars of all ages with the proper care, so fall outs are as rare as with sows; if you use a good rescue, they will support you during the whole life of their rescue piggies. Shops and breeders are only interested in quick money and therefore do neither care about the welfare aspect in selling single piggies nor do they have the time and experience to do careful bonding. Hence you are getting all the silly concepts about boars!
I have already posted a link to the best medical guinea pig website about companionship to show your mum , as well as links to your closest recommendable rescues in your introductions thread.
