Sania is entitled to a reward of 7,50€.
germany
In Germany, to reward honest finders, the finder of an item is entitled to 5% of a lost item's value of up to 500€ under § 971 BGB. Airpods cost about 150 €, so Sania is entitled to a Fider's reward of 7,50 €. Anything more would be at the discretion of Tam, accepting less is at Sania's discretion.
Do note, that denial of the finder's reward at the moment that Sania hands over the item means, that they also deny their entitlement to the reward. In fact, it is upon Sania to demand the reward, and unless they do so, it is presumed that they do not want a finder's reward.
However in making her entitlement to the reward known, Sania may not cross the line into coercion or blackmail (§§ 240, 253 StGB). Should Sania say, without explanation "I demand a payment of 100 € for the airpods", that could be coercion, as she is not entitled to that. If she however says "I am entitled to finder's reward of 7,50 €, and had expenses of 2.50 € to get the phone to you, therefore you owe me 10 €" the picture is different - that is exactly the amount that the law says she would be owed. This is because atop the actual reward Sania can reclaim reasonable fees, such as the bus fare to get the phone to Tam under § 970 BGB. Under § 972 BGB, Sania does not have to relinquish the item till the reward and expenses have been paid but also does not become the owner of the item.
The Fundbüro
To evade a possible claim for "Unterschlagung von Fundsachen" (~conversion by not reporting a found item), the Fundbüro (Found item's office) exists when the owner can't be made out rapidly. Not only does it calculate the required finder's reward, but also handing it over to the office fulfills the requirement to report a found item that is worth more than 10 € under § 965 BGB. It is customary to store the lost items at the Fundbüro, but that is not required.
To gain the item from the Fundbüro, Tam will have to pay any required handling fees to the office but also gets notice of how much he should pay to Sania as well as her contact details. Sania will get contact details of Tam in return, together with a notice that she has a claim to a reward of such value. Should Sania not have given her details, it is presumed that she did not want the finder's reward.
If Sania retained the item, the Fundbüro will inform Tam of the estimated finder's reward and contact details for Sania, so Tam can reclaim the item.