Need more information. Guessing she is in Manulife InvestReady either 1st or 2nd series. What are the UTs that she bought?
The UTs should have been doing fairly well since 2016. Look at
https://en.wikipedia.org/wiki/MSCI_World you'll see that 2018 was a fairly bad year, but 2017 was a really good year.
The problem with investment plans sold by the insurance companies is that they are designed to lock you in for a significant amount of time. For Manulife InvestReady there are two levels of annual charges one of which expires after 10 years. They give you loyalty bonuses but those are only unlocked after many years of being with them. There are even early surrender charges. I think the units sold to you are based on bid price, but it could also be on offer price which is much much worse - not sure about this have to check.
Because of this we generally recommend using Poems or DollarDex to purchase unit trusts. On these platforms there are zero charges - no sales charge, no platform fee, no redemption fee, no switching fee. They also have a wide range of funds available, but more importantly they include some of our favorite funds from Lion Global that are more passively managed thus have lower management fees.
As for your mom, chances are she's already locked in to the point where it would be a better to just leave it until the end of the lock in period. We'll have to see what funds she's holding to see why they aren't doing as well as you think they should be.