Property is unlikely to be the best choice, because;
a) Property is already your biggest asset, so you’d be very vulnerable to a house price crash
b) Being a landlord has legal responsibilities etc and also a lot of risk (if a tenant stops paying their rent, you could have no income for months but still be incurring costs, houses can subside etc).
c) Property is an extremely illiquid asset. If you suddenly need the money in five years time, you could be forced to sell quickly with a tenant in-situ, which would probably be at a huge loss.
Still, the biggest question for a property investment would be whether you will use the money as a deposit for an interest only mortgage (gearing), or just buy outright (ungeared). The returns on an ungeared property investment wouldn’t normally be worth the effort and risk. Gearing can produce good returns, but of course the risk is increased.
Investing in a diverse share portfolio is probably a better idea. You could pay an independent financial advisor to help you set up a sensible investment portfolio (no need to pay them a continual management charge if you don’t want to). On average, historically, shares return much more than an ungeared property portfolio, as well as being a lot simpler and easier to manage and accessible in an emergency.
If she really does want to invest in property, she should at least do some basic training at one of the landlord’s associations on the legal aspects of being a landlord (yes you can get a property agent, but the legal relationship is always between the landlord and the tenant). But really, in terms of financial management there really is little sense right now in this course of action.