Sorry to hear about your mum, going through a similar situation myself so I know how difficult it is.
You may get more on ebay because of the bidding process, if two people (or more) fall in love with it then they will compete to win it, of course it doesn't always work out that way. Also you need to factor in ebays fees. On here you'll need to set a firm asking price, although you can then leave it open to offers, no fees of course and you'll know the bike is going to a true enthusiast.
You can always do both, just bear in mind that you won't always get what you think it's worth, times are hard right now and for many people luxury purchases are off the table, and there are a lot of nice old bikes appearing on the market as people look to raise money, the market certainly isn't like it was at its peak during the lockdown unless we are talking very rare boutique pieces, the rich are always recession proof.
It's a lovely old bike that will definitely appeal to someone, good luck with the sale.
