Rice milk is nutritionally equivilent to juice- fine in moderation, unlikely to trigger allergies, but in no way appropriate as a breast milk substitute. It's way too low in protein and fat.
Commercial almond milk isn't much better- the unsweetened variety is extremely low in calories, and the sweetened version is too high in sugar.
If breastmilk is truly unavailable, then toddlers need the milk of another mammal, or formula. If the baby is allergic to cow's milk, then goat or sheep milk is an option. Goat milk is easier to locate, at least in my area. Raw milk is generally better than pasturized milk, but is harder to obtain. There are plenty of recipes for homemade infant formula based on raw milk, and many parents use those formulas for toddlers as well as infants, or a mixture of formula and whole milk.
The absolute best milk for toddlers is fresh human milk. I don't know your whole situation, but you might want to reconsider weaning if possible.